epca: fix test_bit parameters

Switch from ASYNC_* to ASYNCB_*, because test_bit expects
bit number, not mask.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>