V4L/DVB (4972): Dvb-core: fix bug in CRC-32 checking on 64-bit systems

CRC-32 checking during ULE decapsulation always failed on x86_64 systems due
to the size of a variable used to store CRC. This bug was discovered on
Fedora Core 6 with kernel-2.6.18-1.2849. The i386 counterpart has no such
problem. This patch has been tested on 64-bit system as well as 32-bit system.

Signed-off-by: Ang Way Chuang <wcang@nrg.cs.usm.my>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>