broadcom/compiler: fix postponed TMU spills with multiple writes

broadcom/compiler: fix postponed TMU spills with multiple writes

If we are spilling a register that is used in the middle of a TMU
sequence, we postpone the spill until the TMU sequence finishes,
at which point we inject the spill and rewrite the original
instruction to write to the new temp.

However, this doesn't work if the register is written multiple
times during the TMU sequence. In that scenario, we need to ensure
that all writes are rewritten to use the new temp, not just the last
one.

Cc: mesa-stable
Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17201>