staging: rtl8723bs: add spaces around operator

fix the following post-commit hook checkpatch warning:

CHECK: spaces preferred around that '+' (ctx:VxV)
29: FILE: drivers/staging/rtl8723bs/hal/rtl8723b_hal_init.c:2238:
+			hal_get_chnl_group_8723b(ch+1, &group);

Signed-off-by: Fabio Aiuto <fabioaiuto83@gmail.com>
Link: https://lore.kernel.org/r/e9f65e7600a3c935ef9c310e782790e04cc1f17f.1626874164.git.fabioaiuto83@gmail.com


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