ALSA: usb-audio: Fix packet size calculation

Commit f0bd62b640 ("ALSA: usb-audio: Improve frames size computation")
introduced a regression for devices which have playback endpoints with
bInterval > 1. Fix this by taking ep->datainterval into account.

Note that frame and fps are actually mean packet and packets per second
in the code introduces by the mentioned commit. This will be fixed in a
follow-up patch.

Fixes: f0bd62b640 ("ALSA: usb-audio: Improve frames size computation")
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=208353
Signed-off-by: Alexander Tsoy <alexander@tsoy.me>
Link: https://lore.kernel.org/r/20200629025934.154288-1-alexander@tsoy.me
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/endpoint.c

@@ -1093,6 +1093,7 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
 		ep->freqn = get_usb_high_speed_rate(rate);
 		ep->fps = 8000;
 	}
+	ep->fps >>= ep->datainterval;
 
 	ep->sample_rem = rate % ep->fps;
 	ep->framesize[0] = rate / ep->fps;