V4L/DVB (13079): dib0700: fixed xc2028 firmware loading kernel oops

Fixing kernel oops when driver attemps to load xc2028 firmware.

Note by djh: the patch contribute by Martin is a port of a fix I made during
the PCTV 340e development.  It's a temporary workaround that fixes a regression
(an OOPS condition) and the real fix should be in the code that manages the
i2c master on the dib7000p.  But this fix does address the immmediate
regression and should be merged upstream until we do a cleaner fix.

Signed-off-by: Martin Samek <martin@marsark.sytes.net>
Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
CC: stable@kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>