freedreno: stop frob'ing pipe_resource::nr_samples

Previously we tried to normalize nr_samples to MAX2(1, nr_samples) to
avoid having to deal with 0 vs 1 everywhere.  But this causes problems
in mesa/st, for example st_finalize_texture() will think there is a
nr_samples mismatch and recreate the texture.  Somehow this manifests
as corrupt x11 font rendering on generations that do not support MSAA
(but apparently works fine on a5xx and a6xx which do support MSAA.)

Fixes: cf0c7258 freedreno/a5xx: MSAA
Signed-off-by: Rob Clark <robdclark@gmail.com>
(cherry picked from commit c3baa077)
[Emil Velikov: resolve trivial conflicts]
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>

Conflicts:
	src/gallium/drivers/freedreno/freedreno_batch_cache.c