[media] staging: as102: Replace pragma(pack) with attribute __packed

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