ALSA: emu10k1: make snd_emu1010_load_firmware_entry() void

There is only one call site, and there we already know that we actually
have a firmware.

Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Message-ID: <20240428093717.3198716-3-oswald.buddenhagen@gmx.de>