V4L/DVB (11243): cx88: Missing failure checks

The ioremap one was reported in October 2007 (Bug 9146), the kmalloc one
was blindingly obvious while looking at the ioremap one

The bug suggests some other configuration for lots of I/O memory (32MB per
device is ioremapped) but I'll leave that to the real maintainers

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>