staging: rtl8712: Annotate r8712_sitesurvey_cmd()

Add __must_hold() sparse annotation to r8712_sitesurvey_cmd(),
replacing the comments on top of the function.

Signed-off-by: Mauro Dreissig <mukadr@gmail.com>
Link: https://lore.kernel.org/r/20200705180944.20958-1-mukadr@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>