staging: wilc1000: return zero on success and non-zero on function failure

staging: wilc1000: return zero on success and non-zero on function failure

Some of the HIF layer API's return zero for failure and non-zero for
success condition. Now, modified the functions to return zero for success
and non-zero for failure as its recommended approach suggested in [1].

1. https://lore.kernel.org/driverdev-devel/20191113183322.a54mh2w6dulklgsd@kili.mountain/

Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
Link: https://lore.kernel.org/r/20200123182129.4053-1-ajay.kathat@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>