net: marvell: fix a missing check of acpi_match_device

When acpi_match_device fails, its return value is NULL. Directly using
the return value without a check may result in a NULL-pointer
dereference. The fix checks if acpi_match_device fails, and if so,
returns -EINVAL.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>