staging: rtl8723bs: remove set but not used variable 'FirstConnect'

staging: rtl8723bs: remove set but not used variable 'FirstConnect'

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

drivers/staging/rtl8723bs/hal/odm.c: In function 'odm_RSSIMonitorCheckCE':
drivers/staging/rtl8723bs/hal/odm.c:1258:7: warning:
 variable 'FirstConnect' 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/20190731140903.304-1-yuehaibing@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>