Staging: rtl8723au: core: Add braces around macro

This patch fixes the following checkpatch warning:
ERROR: Macros with complex values should be enclosed
in parentheses
1535: FILE: drivers/staging/rtl8723au/core/rtw_mlme.c:1535:

Signed-off-by: Tina Ruchandani <ruchandani.tina@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>