[media] staging: as102: Define device name string pointers constant

Supresses following checkpatch warning:
WARNING: static const char * array should probably be static const char * const

Cc: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Sylwester Nawrocki <snjw23@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>