[media] cpia2: Fix some gcc 4.6 warnings when debug is disabled

cpia2_core.c:529:14: warning: variable 'dir' set but not used [-Wunused-but-set-variable]
cpia2_core.c:526:5: warning: variable 'block_index' set but not used [-Wunused-but-set-variable]

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>