ALSA: hda/realtek - Fixup headphone noise via runtime suspend

commit dad3197da7a3817f27bb24f7fd3c135ffa707202 upstream.

Dell platform with ALC298.
system enter to runtime suspend. Headphone had noise.
Let Headset Mic not shutup will solve this issue.

[ Fixed minor coding style issues by tiwai ]

Signed-off-by: Kailang Yang <kailang@realtek.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>