diag: Add support for 9615, 8260A, and 8974 targets

Also re-structures the code so that adding new target
support will be easier.

Change-Id: I5ad9100932da5454afbf1c996d71a6338dc59dbb
Signed-off-by: Shalabh Jain <shalabhj@codeaurora.org>
3 files changed