Currently if just "dfltcc" is passed as a kernel command line option
"val" going to be NULL, this leads to reading at address 0 in
strcmp(val, "off")

Fix that by making sure "val" is not NULL. This does not affect option
handling logic.
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>