staging: rtl8192e: remove set but not used variable 'payload '

staging: rtl8192e: remove set but not used variable 'payload '

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

drivers/staging/rtl8192e/rtllib_rx.c: In function rtllib_rx_InfraAdhoc:
drivers/staging/rtl8192e/rtllib_rx.c:1303:6: warning:
 variable payload set but not used [-Wunused-but-set-variable]

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20190717143551.29200-1-yuehaibing@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>