nir: fix assign_io_var_locations for vertex inputs

Also fixes fragment inputs using the wrong "base" value (which was working
only because FRAG_RESULT_DATA0 is less than VARYING_SLOT_VAR0)

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Reviewed-by: Eric Anholt <eric@anholt.net>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3108>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3108>
1 file changed