The PRM says "The execution size must be 1." In 73137997e2, the
execution size was set to 1 when it should have been BRW_EXECUTE_1
(which maps to 0). Later, in dc2d3a7f5c, JMPI was used for
line AA on gen6 and earlier and we started manually stomping the
exeution size to BRW_EXECUTE_1 in the generator. This commit fixes the
original bug and makes brw_JMPI just do the right thing.
Reviewed-by: Matt Turner <mattst88@gmail.com>
Fixes: 73137997e2
(cherry picked from commit 562b8d458c)