pinctrl: armada-37xx: Fix number of pin in south bridge

On the south bridge we have pin from to 29, so it gives 30 pins (and not
29).

Without this patch the kernel complain with the following traces:
cat /sys/kernel/debug/pinctrl/d0018800.pinctrl/pingroups
[  154.530205] armada-37xx-pinctrl d0018800.pinctrl: failed to get pin(29) name
[  154.537567] ------------[ cut here ]------------
[  154.542348] WARNING: CPU: 1 PID: 1347 at /home/gclement/open/kernel/marvell-mainline-linux/drivers/pinctrl/core.c:1610 pinctrl_groups_show+0x15c/0x1a0
[  154.555918] Modules linked in:
[  154.558890] CPU: 1 PID: 1347 Comm: cat Tainted: G        W       4.13.0-rc1-00001-g19e1b9fa219d #525
[  154.568316] Hardware name: Marvell Armada 3720 Development Board DB-88F3720-DDR3 (DT)
[  154.576311] task: ffff80001d32d100 task.stack: ffff80001bdc0000
[  154.583048] PC is at pinctrl_groups_show+0x15c/0x1a0
[  154.587816] LR is at pinctrl_groups_show+0x148/0x1a0
[  154.592847] pc : [<ffff0000083e3adc>] lr : [<ffff0000083e3ac8>] pstate: 00000145
[  154.600840] sp : ffff80001bdc3c80
[  154.604255] x29: ffff80001bdc3c80 x28: 00000000f7750000
[  154.609825] x27: ffff80001d05d198 x26: 0000000000000009
[  154.615224] x25: ffff0000089ead20 x24: 0000000000000002
[  154.620705] x23: ffff000008c8e1d0 x22: ffff80001be55700
[  154.626187] x21: ffff80001d05d100 x20: 0000000000000005
[  154.631667] x19: 0000000000000006 x18: 0000000000000010
[  154.637238] x17: 0000000000000000 x16: ffff0000081fc4b8
[  154.642726] x15: 0000000000000006 x14: ffff0000899e537f
[  154.648214] x13: ffff0000099e538d x12: 206f742064656c69
[  154.653613] x11: 6166203a6c727463 x10: 0000000005f5e0ff
[  154.659094] x9 : ffff80001bdc38c0 x8 : 286e697020746567
[  154.664576] x7 : ffff000008551870 x6 : 000000000000011b
[  154.670146] x5 : 0000000000000000 x4 : 0000000000000000
[  154.675544] x3 : 0000000000000000 x2 : 0000000000000000
[  154.681025] x1 : ffff000008c8e1d0 x0 : ffff80001be55700
[  154.686507] Call trace:
[  154.688668] Exception stack(0xffff80001bdc3ab0 to 0xffff80001bdc3be0)
[  154.695224] 3aa0:                                   0000000000000006 0001000000000000
[  154.703310] 3ac0: ffff80001bdc3c80 ffff0000083e3adc ffff80001bdc3bb0 00000000ffffffd8
[  154.711304] 3ae0: 4554535953425553 6f6674616c703d4d 4349564544006d72 6674616c702b3d45
[  154.719478] 3b00: 313030643a6d726f 6e69702e30303838 ffff80006c727463 ffff0000089635d8
[  154.727562] 3b20: ffff80001d1ca0cb ffff000008af0fa4 ffff80001bdc3b40 ffff000008c8e1dc
[  154.735648] 3b40: ffff80001bdc3bc0 ffff000008223174 ffff80001be55700 ffff000008c8e1d0
[  154.743731] 3b60: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
[  154.752354] 3b80: 000000000000011b ffff000008551870 286e697020746567 ffff80001bdc38c0
[  154.760446] 3ba0: 0000000005f5e0ff 6166203a6c727463 206f742064656c69 ffff0000099e538d
[  154.767910] 3bc0: ffff0000899e537f 0000000000000006 ffff0000081fc4b8 0000000000000000
[  154.776085] [<ffff0000083e3adc>] pinctrl_groups_show+0x15c/0x1a0
[  154.782823] [<ffff000008222abc>] seq_read+0x184/0x460
[  154.787505] [<ffff000008344120>] full_proxy_read+0x60/0xa8
[  154.793431] [<ffff0000081f9bec>] __vfs_read+0x1c/0x110
[  154.799001] [<ffff0000081faff4>] vfs_read+0x84/0x140
[  154.803860] [<ffff0000081fc4fc>] SyS_read+0x44/0xa0
[  154.808983] [<ffff000008082f30>] el0_svc_naked+0x24/0x28
[  154.814459] ---[ end trace 4cbb00a92d616b95 ]---

Cc: stable@vger.kernel.org
Fixes: 87466ccd ("pinctrl: armada-37xx: Add pin controller support
for Armada 37xx")
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>