pinctrl: armada-37xx: fix control of pins 32 and up

The 37xx configuration registers are only 32 bits long, so
pins 32-35 spill over into the next register.  The calculation
for the register address was done, but the bitmask was not, so
any configuration to pin 32 or above resulted in a bitmask that
overflowed and performed no action.

Fix the register / offset calculation to also adjust the offset.

Fixes: 5715092a

 ("pinctrl: armada-37xx: Add gpio support")
Signed-off-by: Patrick Williams <alpawi@amazon.com>
Acked-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191001154634.96165-1-alpawi@amazon.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>