ALSA: hda/hdmi: Consider ELD is invalid when no SAD is present

ALSA: hda/hdmi: Consider ELD is invalid when no SAD is present

BugLink: https://bugs.launchpad.net/bugs/1953208
There's a system that reports a bogus HDMI audio interface:
$ cat eld#2.0
monitor_present         1
eld_valid               1
monitor_name
connection_type         DisplayPort
eld_version             [0x2] CEA-861D or below
edid_version            [0x3] CEA-861-B, C or D
manufacture_id          0xe430
product_id              0x690
port_id                 0x0
support_hdcp            0
support_ai              0
audio_sync_delay        0
speakers                [0xffff] FL/FR LFE FC RL/RR RC FLC/FRC RLC/RRC FLW/FRW FLH/FRH TC FCH
sad_count               0

Since playing audio is not possible without SAD, also consider ELD is
invalid for this case.

(cherry picked from commit 256a9e734ba57d3b62cbcf700f59920d200d1745 linux-next)
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>