nvc0/ir: fix TargetNVC0::insnCanLoadOffset()

Previously, TargetNVC0::insnCanLoadOffset() returned whether the offset
could be set to a specific value. The IndirectPropagation pass expected
it to return whether the offset could be increased by a specific value,
which is what TargetNV50::insnCanLoadOffset() does.

Fixes: 37b67db6
	("nvc0/ir: be careful about propagating very large offsets into const load")

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Karol Herbst <kherbst@redhat.com>
(cherry picked from commit 6bb0f87c)