winsys/svga: Fix RELOC_INTERNAL mob GPU access

winsys/svga: Fix RELOC_INTERNAL mob GPU access

SVGA_RELOC_INTERNAL indicates a transfer between surface and backing mob.
This means that if the GPU for example reads from the surface it writes
to the backing mob. But since the buffer mapping code allows for
simultaneous gpu- and cpu read access, a read from the surface to the mob
will not synchronize a subsequent map to the readback.

Fix this by inverting the mob access mode in a surface relocation with
SVGA_RELOC_INTERNAL set.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Charmaine Lee <charmainel@vmware.com>