rtlwifi: rtl8188ee: remove Comparison to bool in rf.c

Fix the following coccicheck warning:

drivers/net/wireless/realtek/rtlwifi/rtl8188ee/rf.c:476:6-14: WARNING:
Comparison to bool
drivers/net/wireless/realtek/rtlwifi/rtl8188ee/rf.c:54:5-22: WARNING:
Comparison to bool

Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200504113321.41118-1-yanaijie@huawei.com