media: dm1105: Limit number of cards to avoid buffer over read

dm1105_probe() counts number of cards at dm1105_devcount,
but missed bounds check before dereference a card array.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Anton Vasilyev <vasilyev@ispras.ru>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>