MFC r278004:

MFC r278004:

Constify a number of accesses in drm2's radeon drivers to avoid
-Wcast-qual warnings.  No functional change.

Reviewed by:	dumbbell
Differential Revision: https://reviews.freebsd.org/D1727

MFC r278438:

After r278004 was committed, Bruce Evans noted that the casts were
actually completely unnecessary, here:

https://lists.freebsd.org/pipermail/svn-src-all/2015-February/098478.html

Remove the casts, and just assign &xxx_io_mc_regs[0][0] directly.

Reviewed by:	dumbbell
Differential Revision: https://reviews.freebsd.org/D1748

git-svn-id: svn://svn.freebsd.org/base/stable/10@278617 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f