staging: r8188eu: call _cancel_timer_ex from _rtw_free_recv_priv

staging: r8188eu: call _cancel_timer_ex from _rtw_free_recv_priv

The _rtw_init_recv_priv() initializes precvpriv->signal_stat_timer and
sets it's timeout interval to 1000 ms. But _rtw_free_recv_priv()
doesn't cancel the timer and we need to explicitly call
_cancel_timer_ex() after we call _rtw_free_recv_priv() to cancel the
timer.
Call _cancel_timer_ex() from inside _rtw_free_recv_priv() as every init
function needs a matching free function.

Signed-off-by: Vihas Makwana <makvihas@gmail.com>
Link: https://lore.kernel.org/r/20220309205047.45981-2-makvihas@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>