zink: set UBO alignments in nir_intrinsic_load_uniform lowering

zink: set UBO alignments in nir_intrinsic_load_uniform lowering

resolves this error
  error: nir_intrinsic_align_offset(instr) < nir_intrinsic_align_mul(instr) (../src/compiler/nir/nir_validate.c:582)
in ext_packed_depth_stencil-readdrawpixels piglit test

port of f5b14d983e5afa1b8f75e6f3692830a1ee46d1df

Fixes: fb64954d9dd ("nir: Validate that memory load/store ops work on whole bytes")
Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4711>