Revert "snd_tlv_convert_to_dB: Fix mute handling for MINMAX_MUTE type"

Revert "snd_tlv_convert_to_dB: Fix mute handling for MINMAX_MUTE type"

This reverts commit 41039b49ad3e20506134864028c77aeaba4c0d51.

SND_CTL_TLVT_DB_MINMAX_MUTE means that the hardware is muted on lowest
hardware volume value (not on lowest dB value).

Analysis:

Range:  min=0, max=7248
dB:     min=-2837, max=-6
dB span: 2831 centibels (28.31 dB)

Volume | After revert/origin | PR#478 behavior
-------|---------------------|----------------------
     0 |  MUTE               | MUTE
     1 |  -2837 (-28.37 dB)  | MUTE <- DIFFERS!
     2 |  -2837 (-28.37 dB)  | MUTE <- DIFFERS!
     5 |  -2836 (-28.36 dB)  |  -2836 (-28.36 dB)
    10 |  -2834 (-28.34 dB)  |  -2834 (-28.34 dB)
    50 |  -2818 (-28.18 dB)  |  -2818 (-28.18 dB)

Range:  min=0, max=999
dB:     min=0, max=390
dB span: 390 centibels (3.90 dB)

Volume | After revert/origin | PR#478 behavior
-------|---------------------|----------------------
     0 | MUTE                | MUTE
     1 |      0 (0.00 dB)    | MUTE <- DIFFERS!
     2 |      0 (0.00 dB)    | MUTE <- DIFFERS!
     5 |      1 (0.01 dB)    |      1 (0.01 dB)
    10 |      3 (0.03 dB)    |      3 (0.03 dB)
    50 |     19 (0.19 dB)    |     19 (0.19 dB)

Fixes: https://github.com/alsa-project/alsa-lib/issues/504
Link: https://github.com/alsa-project/alsa-lib/pull/478
Signed-off-by: Jaroslav Kysela <perex@perex.cz>