staging: rtl8723bs: Replace string with identifier

Replace the hardcoded function name with its predefined identifier.

Signed-off-by: Javier F. Arias <jarias.linux@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Link: https://lore.kernel.org/r/20191008214851.p4w7cbpuldnwkne4@gmail.com


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