ALSA: usb: fpc: replace kmalloc_array followed by copy_from_user with memdup_array_user

Replace kmalloc_array() followed by copy_from_user() with
memdup_array_user() to improve and simplify fcp_ioctl_set_meter_map().

No functional changes intended.

Signed-off-by: Pedro Demarchi Gomes <pedrodemargomes@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>