diag: Configure diag over STM for APPS by HW ACCEL command

Extend support to configure diag over STM using HW ACCEL command
for APPS.

Change-Id: Ifd9bf9867e910e9df4e1b6bddd94012c82f2be4f
Signed-off-by: Manoj Prabhu B <bmanoj@codeaurora.org>