radeon_replay/radeon_dp_aux.c: rename to aruba_dp_aux.c

From now on, we want to prefix all the code that we later want to
integrate into coreboot and linux to something that distinguishes it.

The functions in this file are specific to Radeon GPUs codenamed ARUBA,
hence the tropical filename.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>