staging: rtl8723bs: core: Remove unneeded declaration WFD_OUI

Remove unneeded declaration "extern unsigned char WFD_OUI"

Signed-off-by: Hariprasad Kelam <hariprasad.kelam@gmail.com>
Link: https://lore.kernel.org/r/20190819165705.GA5782@hari-Inspiron-1545


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