net: mellanox: mlxbf_gige: Replace non-standard interrupt handling

Since the GPIO driver (gpio-mlxbf2.c) supports interrupt handling,
replace the custom routine with simple IRQ request.

Signed-off-by: Asmaa Mnebhi <asmaa@nvidia.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>