nv50: Clear nv50_ir_prog_info of dead and codegen specific variables

nv50: Clear nv50_ir_prog_info of dead and codegen specific variables

These variables are either not used in the code, only assigned but
never accessed, or only used inside codegen. Another reason is that this
patch will be preceding shader cache, and these variables are useless to
cache. Removing/moving them should make it clearer by removing the case something
from the structure is not cached.

Shader cache patch: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4264

Signed-off-by: Mark Menzynski <mmenzyns@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5697>