nir/lower_ssbo: Don't set align_* for atomics
Fixes crashes when lowering atomic SSBOs:
run: ../src/compiler/nir/nir.h:1875: nir_intrinsic_align_mul: Assertion `info->index_map[NIR_INTRINSIC_ALIGN_MUL] > 0' failed.
Signed-off-by: Alyssa Rosenzweig alyssa.rosenzweig@collabora.com