[ALSA] Export missing snd_pcm_format_*()

PCM Midlevel
Export snd_pcm_format_size().  This function is used by some out-of-kernel
drivers.

Make snd_pcm_format_cpu_endian() macro for optimization.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index a2757fc..d57f4ec 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -1069,6 +1069,7 @@
 EXPORT_SYMBOL(snd_pcm_format_big_endian);
 EXPORT_SYMBOL(snd_pcm_format_width);
 EXPORT_SYMBOL(snd_pcm_format_physical_width);
+EXPORT_SYMBOL(snd_pcm_format_size);
 EXPORT_SYMBOL(snd_pcm_format_silence_64);
 EXPORT_SYMBOL(snd_pcm_format_set_silence);
 EXPORT_SYMBOL(snd_pcm_build_linear_format);