[ALSA] usb-audio: add workaround for broken E-Mu frequency feedback

Add a workaround for the feedback pipe of E-Mu 0202/0404 USB devices
that reports the number of samples per packet instead of the number of
samples per microframe.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>