Make epca fail on initialization failure instead of panic.

Cc: "Digi International, Inc" <Eng.Linux@digi.com>
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Acked-by: NAlan Cox <alan@redhat.com>
Acked-by: NScott Kilau <scottk@digi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>