[media] staging: as102: Enable compilation

[media] staging: as102: Enable compilation

Fix compilation errors in the USB driver by replacing usb_buffer_free(),
usb_buffer_alloc() with usb_free_coherent() and usb_alloc_coherent().
Add entries for the driver in parent Makefile and Kconfig.

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