ALSA: ymfpci: Use common error handling code in snd_card_ymfpci_probe()

* Add a jump target so that a bit of exception handling can be better
  reused at the end of this function.

  This issue was detected by using the Coccinelle software.

* The script "checkpatch.pl" pointed information out like the following.

  ERROR: do not use assignment in if condition

  Thus fix a few source code places.

[ This also fixed a potential use-after-free at error path of
  snd_opl3_hwdep_new(), too -- tiwai ]

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>