staging: rtl8723bs: Improve the comment explaining the locking rules

staging: rtl8723bs: Improve the comment explaining the locking rules

rtw_mlme.h has a comment which briefly describes the locking rules for
the rtl8723bs driver, improve this to also mention the locking order
of xmit_priv.lock vs the lock(s) embedded in the various queues.

Cc: Fabio Aiuto <fabioaiuto83@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20220302101637.26542-2-hdegoede@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>