net: stmmac: fix memory leak during driver probe

commit d7f576dc upstream.

On driver probe, kmemleak reported the following memory leak which was
due to allocated bitmap that was not being freed in stmmac_dvr_probe().

unreferenced object 0xffff9276014b13c0 (size 8):
  comm "systemd-udevd", pid 2143, jiffies 4294681112 (age 116.720s)
  hex dump (first 8 bytes):
    00 00 00 00 00 00 00 00                          ........
  backtrace:
    [<00000000c51e34b2>] stmmac_dvr_probe+0x1c0/0x440 [stmmac]
    [<00000000b530eb41>] intel_eth_pci_probe.cold+0x2b/0x14e [dwmac_intel]
    [<00000000b10f8929>] pci_device_probe+0xd2/0x150
    [<00000000fb254c74>] really_probe+0xf8/0x410
    [<0000000034128a59>] driver_probe_device+0x5d/0x150
    [<00000000016104d5>] device_driver_attach+0x53/0x60
    [<00000000cb18cd07>] __driver_attach+0x96/0x140
    [<00000000da9ffd5c>] bus_for_each_dev+0x7a/0xc0
    [<00000000af061a88>] bus_add_driver+0x184/0x1f0
    [<000000008be5c1c5>] driver_register+0x6c/0xc0
    [<0000000052b18a9e>] do_one_initcall+0x4d/0x210
    [<00000000154d4f07>] do_init_module+0x5c/0x230
    [<000000009b648d09>] load_module+0x2a5a/0x2d40
    [<000000000d86b76d>] __do_sys_finit_module+0xb5/0x120
    [<000000002b0cef95>] do_syscall_64+0x33/0x40
    [<0000000067b45bbb>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: bba2556e ("net: stmmac: Enable RX via AF_XDP zero-copy")
Cc: Ong Boon Leong <boon.leong.ong@intel.com>
Signed-off-by: Wong Vee Khee <vee.khee.wong@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Yongxin Liu <yongxin.liu@windriver.com>