ac/nir: Make intrinsic_name buffer long enough

ac/nir: Make intrinsic_name buffer long enough

When using cmpswap on an image, it was being trunctated to
lvm.amdgcn.image.atomic.cmpswa, with the coords type missing entirely.

v2: Add stable CC

CC: <mesa-stable@lists.freedesktop.org>
Reviewed-by: Grazvydas Ignotas <notasas@gmail.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
(cherry picked from commit 6fc41bb4d59313985f67b1276d1fd1225be09426)