i965: Add a brw_load_register_reg64 helper.

It appears that we can't do this in a single command (like we do for
MI_LOAD_REGISTER_IMM) - the Skylake simulator gets rather grumpy about
the command length if I try to combine them.  No matter.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
2 files changed