wilc1000: remove '-Wunused-but-set-variable' warning in chip_wakeup()

Remove unused variables to avoid the below warnings:

   drivers/net/wireless/microchip/wilc1000/wlan.c: In function 'chip_wakeup':
>> drivers/net/wireless/microchip/wilc1000/wlan.c:620:34: warning: variable 'to_host_from_fw_bit' set but not used [-Wunused-but-set-variable]
     620 |         u32 to_host_from_fw_reg, to_host_from_fw_bit;
         |                                  ^~~~~~~~~~~~~~~~~~~
>> drivers/net/wireless/microchip/wilc1000/wlan.c:620:13: warning: variable 'to_host_from_fw_reg' set but not used [-Wunused-but-set-variable]
     620 |         u32 to_host_from_fw_reg, to_host_from_fw_bit;
         |             ^~~~~~~~~~~~~~~~~~~

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211115102809.1408267-1-ajay.kathat@microchip.com