ir_to_mesa: Fix implementation of ir_binop_equal, ir_binop_notequal.

ir_to_mesa: Fix implementation of ir_binop_equal, ir_binop_notequal.

These binops are the vector-to-bool comparisons, not vec-to-bvec.  We
likely want both operations avilable as expression, since 915 and 965
FS naturally does the vector version, while 965 VS can also naturally
do the scalar version.  However, we can save that until later.

Fixes:
glsl-fs-vec4-operator-equal.shader_test
glsl-fs-vec4-operator-notequal.shader_test
glsl-vs-vec4-operator-equal.shader_test
glsl-vs-vec4-operator-notequal.shader_test