coresight: add memory dump v2 support for etmv4

Add support to CoreSight ETMv4 driver to register for v2 meomory
dump which allows dumping ETMv4 registers in case of device crash
and subsequently parsing their contents from ramdumps.

Change-Id: Ia4af28e0dbe212367796f298d4434265a1433672
Signed-off-by: Aparna Das <adas@codeaurora.org>