rtw88: Fix return value of rtw_wow_check_fw_status

Clang warns that ret is used uninitialzed.
And we found that actually the return type should be "int" instead
of "bool".

Fixes: 44bc17f7 ("rtw88: support wowlan feature for 8822c")
Link: https://github.com/ClangBuiltLinux/linux/issues/850


Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Chin-Yen Lee <timlee@realtek.com>
Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com> # build
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>