All sound/sound_firmware.c contains is mod_firmware_load() that is a legacy
API only used by some OSS drivers.

This patch builds it into an own sound_firmware module that is only built
depending on CONFIG_SOUND_PRIME making the kernel slightly smaller for ALSA
users.

[alan@lxorguk.ukuu.org.uk: comment fix]
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Acked-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>