msm: board-qrd7627a: Enabling RTB for 7627a and 8625.

Enabling RTB(Register Trace Buffer) will help in taking RTB logs. RTB
implements uncached logging of particular events (like readl/writel,
printk, hotplug etc). RTB is useful because it provides a
rough indication of the last events that occured on each core prior to
a crash/reset.

Change-Id: I7b26e2c2b8d012028beaa3d1ed36f85603ad411f
Signed-off-by: Utsab Bose <ubose@codeaurora.org>