staging: rtl8723bs: replace _cancel_timer with del_timer_sync

Replace _cancel_timer with API function del_timer_sync.

One instance of del_timer_sync is moved and an unnecessary pair of spin
locks are removed.

Signed-off-by: Ross Schmidt <ross.schm.dev@gmail.com>
Link: https://lore.kernel.org/r/20201004011743.10750-8-ross.schm.dev@gmail.com


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