ALSA: line6: Tidy up and typo fixes in comments

Just reformatting the comments and typos fixed, no functional
changes.  Particularly,
- avoid the kerneldoc marker "/**",
- reduce multiple comment lines into single lines,
- corrected wrongly referred function names

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

diff --cc sound/usb/line6/driver.c
Simple merge

diff --cc sound/usb/line6/driver.h
Simple merge

diff --cc sound/usb/line6/midi.h
Simple merge

diff --cc sound/usb/line6/pcm.h
Simple merge

diff --cc sound/usb/line6/pod.c
Simple merge

diff --cc sound/usb/line6/podhd.c
Simple merge

diff --cc sound/usb/line6/toneport.c
Simple merge

diff --cc sound/usb/line6/variax.c
Simple merge