video: pxa3xx-gcu: switch to devres functions

Switch to devres allocators to clean up the error unwinding paths.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>