media: s5k6aa: describe some function parameters

[ Upstream commit 070250a1715cee2297de0d9e7e2cea58be999d37 ]

as warned:
  drivers/media/i2c/s5k6aa.c:429: warning: No description found for parameter 's5k6aa'
  drivers/media/i2c/s5k6aa.c:679: warning: No description found for parameter 's5k6aa'
  drivers/media/i2c/s5k6aa.c:733: warning: No description found for parameter 's5k6aa'
  drivers/media/i2c/s5k6aa.c:733: warning: No description found for parameter 'preset'
  drivers/media/i2c/s5k6aa.c:787: warning: No description found for parameter 'sd'

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>