st/mesa: swizzle argument when there's a vector size mismatch

st/mesa: swizzle argument when there's a vector size mismatch

GLSL IR operation arguments can sometimes have an implicit swizzle as a
result of a vector arg and a scalar arg, where the scalar argument is
implicitly expanded to the size of the vector argument.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103955
Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>