Mostly code reorganizations and optimizations for vmwgfx.
- Move TTM code that's only used by vmwgfx to vmwgfx
- Break out the vmwgfx buffer- and resource validation code to a separate source file
- Get rid of a number of atomic operations during command buffer validation.

From: Thomas Hellstrom <thellstrom@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180928131157.2810-1-thellstrom@vmware.com