ALSA: ens1371: Fix "Line In->Rear Out Switch" control

The "Line In->Rear Out Switch" control on ens1371 driver returns a
bogus value, always true, as its check is totally broken.  Fix it to
check the proper GPIO bit mask.

Reported-by: David Binderman <dcb314@hotmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>