staging: wilc1000: fix line over 80 chars in wilc_spi_clear_int_ext()

Refactor wilc_spi_clear_int_ext() to fix the "line over 80 char" issue
reported by checkpatch.pl script.

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