ALSA: korg1212: fix if-statement empty body warnings

Fix gcc warnings when -Wextra is used by using an empty do-while
block instead of <nothing>.  Fixes these build warnings:

../sound/pci/korg1212/korg1212.c:674:44: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../sound/pci/korg1212/korg1212.c:708:43: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../sound/pci/korg1212/korg1212.c:730:43: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../sound/pci/korg1212/korg1212.c:853:43: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../sound/pci/korg1212/korg1212.c:1013:44: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../sound/pci/korg1212/korg1212.c:1035:43: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../sound/pci/korg1212/korg1212.c:1052:43: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../sound/pci/korg1212/korg1212.c:1066:43: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../sound/pci/korg1212/korg1212.c:1087:43: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../sound/pci/korg1212/korg1212.c:1094:43: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../sound/pci/korg1212/korg1212.c:1208:43: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../sound/pci/korg1212/korg1212.c:2360:102: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/91fb1e97-a773-5790-3f65-8198403341e1@infradead.org


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