staging: rtl8723bs: Fix comment on variable init

Change comment from 'local variable' to 'global variables'
and change style to comply with coding-style.

Signed-off-by: Henriette Hofmeier <passt@h-hofmeier.de>
Signed-off-by: Florian Harbecke <florian.harbecke@fau.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>