intel/blorp: Expand blorp_address::offset to be 64 bits.

intel/blorp: Expand blorp_address::offset to be 64 bits.

In the softpin world, surface state base address may be a fixed 64-bit
address (with no associated BO).  It makes sense to store this in the
offset field.  But it needs to be the full size.

We also update the clear color address to be consistently uint64_t
everywhere so we can continue passing intel_miptree_get_clear_color
a pointer to the blorp_address's offset field without type mismatches.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>