ALSA: emu10k1: add error handling for snd_ctl_add

[ Upstream commit 6d531e7b972cb62ded011c2dfcc2d9f72ea6c421 ]

When snd_ctl_add fails, the lack of error-handling code may
cause unexpected results.

This patch adds error-handling code after calling snd_ctl_add.

Signed-off-by: Zhouyang Jia <jiazhouyang09@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>