staging: rtl8723bs: Remove multiple assignments

Remove multiple assignments by factorizing them.
Problem found using checkpatch.pl:-
CHECK: multiple assignments should be avoided

Signed-off-by: Simran Singhal <singhalsimran0@gmail.com>
Link: https://lore.kernel.org/r/20200325142226.GA14711@simran-Inspiron-5558


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