Use right buffer to print to.

PR:		kern/176597
Submitted by:	Christoph Mallon <christoph mallon gmx de>
MFC after:	2 weeks
Unbreak mount_udf by passing the correct iovec length into
nmount().  This has been broken since r247856.

PR:		bin/186193
Submitted by:	Arnot Belohlavek
MFC after:	1 week
Abort when firmware isn't present in R600+ models.

More details at:
http://anonscm.debian.org/viewvc/kernel/dists/trunk/linux/debian/patches/bugfix/all/radeon-firmware-is-required-for-drm-and-kms-on-r600-onward.patch?revision=20909&view=co

Reviewed by:	dumbbell
MFC after:	1 week