msm: pil-q6v5: Add support for QDSP6v55 subsystem

The QDSP6v55 subsystem differs slightly from the QDSP6v5 version. Use the
compatible dt field to indicate this new version.

Change-Id: Idf639dab88fc15f5011eea17bb4cccba0dcaaf20
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>