ALSA: hda/realtek - Fix microphone noise on ASUS TUF B550M-PLUS

Set microphone pins 0x18 (rear) and 0x19 (front) to VREF_50 to fix the
microphone noise on ASUS TUF B550M-PLUS which uses the ALCS1200A codec.
The initial value was VREF_80.

The same issue is also present on Windows using both the default Windows
driver and all tested Realtek drivers before version 6.0.9049.1. Comparing
Realtek driver 6.0.9049.1 (the first one without the microphone noise) to
Realtek driver 6.0.9047.1 (the last one with the microphone noise)
revealed that the fix is the result of setting pins 0x18 and 0x19 to
VREF_50.

This fix may also work for other boards that have been reported to have
the same microphone issue and use the ALC1150 and ALCS1200A codecs, since
these codecs are similar and the fix in the Realtek driver on Windows is
common for both. However, it is currently enabled only for ASUS TUF
B550M-PLUS as this is the only board that could be tested.

Signed-off-by: Marios Levogiannis <marios.levogiannis@gmail.com>
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