gallium: add support for LODQ opcodes.

This opcode provide support for GL_ARB_texture_query_lod,

Signed-off-by: Dave Airlie <airlied@redhat.com>
[imirkin: rebase, docs update]
Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
st/mesa: add support for ARB_texture_query_lod

Add support for the LODQ texture instruction.

Signed-off-by: Dave Airlie <airlied@redhat.com>
nv50: enable texture query lod

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>