V4L/DVB: cx25821: fix coding style issues in cx25821-core.c

Fixes up warnings and errors found by the checkpatch.pl tool on
cx25821-core.c.
Signed-off-by: Olimpiu Pascariu <olimpiu.pascariu@gmail.com>
CC: Palash Bandyopadhyay <palash.bandyopadhyay@conexant.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>