ALSA: usb-audio: Add missing ep_idx in fixed EP quirks

The quirk entry for Focusrite Saffire 6 had no proper ep_idx for the
capture endpoint, and this confused the driver, resulting in the
broken sound.  This patch adds the missing ep_idx in the entry.

While we are at it, a couple of other entries (for Digidesign MBox and
MOTU MicroBook II) seem to have the same problem, and those are
covered as well.

Fixes: bf6313a0 ("ALSA: usb-audio: Refactor endpoint management")
Reported-by: André Kapelrud <a.kapelrud@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220521065325.426-1-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/quirks-table.h

@@ -2672,6 +2672,7 @@ YAMAHA_DEVICE(0x7010, "UB99"),
 					.altset_idx = 1,
 					.attributes = 0,
 					.endpoint = 0x82,
+					.ep_idx = 1,
 					.ep_attr = USB_ENDPOINT_XFER_ISOC,
 					.datainterval = 1,
 					.maxpacksize = 0x0126,
@@ -2875,6 +2876,7 @@ YAMAHA_DEVICE(0x7010, "UB99"),
 					.altset_idx = 1,
 					.attributes = 0x4,
 					.endpoint = 0x81,
+					.ep_idx = 1,
 					.ep_attr = USB_ENDPOINT_XFER_ISOC |
 						USB_ENDPOINT_SYNC_ASYNC,
 					.maxpacksize = 0x130,
@@ -3391,6 +3393,7 @@ YAMAHA_DEVICE(0x7010, "UB99"),
 					.altset_idx = 1,
 					.attributes = 0,
 					.endpoint = 0x03,
+					.ep_idx = 1,
 					.rates = SNDRV_PCM_RATE_96000,
 					.ep_attr = USB_ENDPOINT_XFER_ISOC |
 						   USB_ENDPOINT_SYNC_ASYNC,