staging: wilc1000: remove 'cmd' variable in wilc_spi functions

Cleanup patch to remove the 'cmd' variable in wilc_spi.c. Instead of
using cmd now passing the command directly.

Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>