panfrost/midgard: Fix 1-arg ALU memory corruption

panfrost/midgard: Fix 1-arg ALU memory corruption

Certain ops that only take one argument have an imaginary "zero"
constant for their second argument. For instance, conversions:

   i2f [dest], [source], #0

Memory corruption meant that #0 was instead random noise. For some ops,
that doesn't matter (manifested as abnormally large code size and poor
scheduling due to extra constants in random places). But for others,
where a 1-op is emulated by a 2-op with an implicit 0 second argument,
that broke things.

Fixes iabs (emulated by iabsdiff).

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-By: Ryan Houdek <Sonicadvance1@gmail.com>