staging: wilc1000: fix build warning with setup_timer()

I forgot to properly cast a pointer to unsigned long in a conversion to
setup_timer() which resulted in a build warning.  Fix that up.

Cc: Johnny Kim <johnny.kim@atmel.com>
Cc: Rachel Kim <rachel.kim@atmel.com>
Cc: Dean Lee <dean.lee@atmel.com>
Cc: Chris Park <chris.park@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>