staging: wilc1000: remove extraneous variable

Building wilc1000 with clang currently fails in the staging-next branch:

drivers/staging/wilc1000/wilc_spi.c:123:34: warning: tentative definition of variable with internal linkage has incomplete non-array type 'const struct wilc1000_ops' [-Wtentative-definition-incomplete-type]
static const struct wilc1000_ops wilc1000_spi_ops;

The reason is that wilc1000_ops was left behind after a recent cleanup,
and is completely unused and also uninitialized and const and has an
incomplete type.

Removing the variable is obviously correct, and gets rid of the warning.
No idea why gcc does not complain about it though.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>