ALSA: emu10k1: drop redundant snd_emu10k1_efx_playback_pointer()

It's just an (outdated) copy of snd_emu10k1_playback_pointer().

Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Link: https://lore.kernel.org/r/20230421141006.1005452-2-oswald.buddenhagen@gmx.de


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