intel/decoder: Make get_state_size take a full 64-bit address and a base

intel/decoder: Make get_state_size take a full 64-bit address and a base

i965 wants to use an offset from a base because everything is in a
single buffer whose address may be relocated, and all base addresses
are set to the start of that buffer.

iris wants to use a full 64-bit address, because state lives in separate
buffers which may be in the shader, surface, and dynamic memory zones,
where addresses grow downward from the top of a 4GB zone,  So it's very
possible for a 32-bit offset to exist relative to multiple bases,
leading to the wrong state size.