nir/ lower_int_to_float: Handle umax and umin

nir/ lower_int_to_float: Handle umax and umin

8e1b75b3 introduced umax/umin in order to lower iand/ior for (n)eq zero.
That breaks the lower_int_to_float pass, because umax and umin weren't
handled there.

Tested with lima. The other users of nir_lower_int_to_float
(etnaviv, freedreno) should also have that issue.

Reviewed-by: Vasily Khoruzhick <anarsoul@gmail.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Andreas Baierl <ichgeh@imkreisrum.de>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6043>