ALSA: scarlett2: Add Gen 4 firmware 2417 autogain status text

Firmware 2417 for the Scarlett 4th Gen 2i2 and 4i4 added a new
autogain exit code ("Root"). Without this entry the new status is
reported as "Invalid".

Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/c62bb12106d143fa71ceb3be4502221a34b35c18.1777153011.git.g@b4.vu

Author: geoffreybennett

sound/usb/mixer_scarlett2.c

@@ -398,6 +398,7 @@ static const char *const scarlett2_autogain_status_gen4[] = {
 	"FailMaxGainLimit",
 	"FailClipped",
 	"Cancelled",
+	"Root",
 	"Invalid",
 	NULL
 };