ALSA: scarlett2: Fix Scarlett 4th Gen input gain range again

The 4th Gen input preamp gain range is 0dB to +69dB, although the
control values range from 0 to 70. Replace SCARLETT2_MAX_GAIN with
SCARLETT2_MAX_GAIN_VALUE and SCARLETT2_MAX_GAIN_DB, and update the TLV
again.

Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Fixes: a45cf0a0 ("ALSA: scarlett2: Fix Scarlett 4th Gen input gain range")
Message-ID: <Ze7OMA8ntG7KteGa@m.b4.vu>
Signed-off-by: Takashi Iwai <tiwai@suse.de>