ALSA: pcm: remove unused variable from snd_pcm_info()

Remove unused 'runtime' variable from function snd_pcm_info().
The last usage of this variable was removed with the
'commit e11f0f90a626f9 ("ALSA: pcm: remove SNDRV_PCM_IOCTL1_INFO
internal command")'.

Change-Id: I3964d84f7cced811d15ff45a1c31cc28d20dc721
Signed-off-by: Banajit Goswami <bgoswami@codeaurora.org>