staging: rtl8723au: rtl8723a_bt-coexist.c: Remove unnecessary #ifdef CONFIG_8723AU_BT_COEXIST

This file is only compiled if CONFIG_8723AU_BT_COEXIST=y

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>