staging: rtlwifi: Remove set but not used variable 'ppsc'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/staging/rtlwifi/btcoexist/halbtcoutsrc.c: In function 'halbtc_leave_lps':
drivers/staging/rtlwifi/btcoexist/halbtcoutsrc.c:284:21: warning:
 variable 'ppsc' set but not used [-Wunused-but-set-variable]

drivers/staging/rtlwifi/btcoexist/halbtcoutsrc.c: In function 'halbtc_enter_lps':
drivers/staging/rtlwifi/btcoexist/halbtcoutsrc.c:307:21: warning:
 variable 'ppsc' set but not used [-Wunused-but-set-variable]

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>