staging: rtl8723bs: remove unused variable pwrctl

staging: rtl8723bs: remove unused variable pwrctl

GCC reports the following warning with W=1:

drivers/staging/rtl8723bs/hal/rtl8723b_cmd.c:532:23: warning:
 variable 'pwrctl' set but not used [-Wunused-but-set-variable]
   532 |  struct pwrctrl_priv *pwrctl;
       |                       ^~~~~~

This variable is not used so remove it to fix the warning.

Signed-off-by: Pu Lehui <pulehui@huawei.com>
Link: https://lore.kernel.org/r/20210409045728.125852-1-pulehui@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>