ALSA: usb-audio: fix spelling mistake "Frequence" -> "Frequency"

There are spelling mistakes in equalizer name fields, fix them.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20181125231208.14350-1-colin.king@canonical.com


Signed-off-by: Takashi Iwai <tiwai@suse.de>