staging: rtl8723bs: rename get_ra() due to global symbol collision

Turns out that powerpc already has a get_ra() function, which conflicts
with this staging driver's inlined function (which is just picking a
byte out of an array for some odd reason), so rename it to fix the
powerpc build as that's the more important thing here.

Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/20210520064801.1961972-1-gregkh@linuxfoundation.org


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