ALSA: rawmidi: (cosmetic) align function parameters

fix cppcheck:

sound/core/rawmidi.c:1711:49: style:inconclusive: Function
'snd_rawmidi_free' argument 1 names different: declaration 'rawmidi'
definition 'rmidi'. [funcArgNamesDifferent]

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200902212133.30964-16-pierre-louis.bossart@linux.intel.com


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