ARM: dts: qcom: Add mem mapped timer devices to 8994

Mem-mapped timers are used to consolidate the timer interrupts across all
cpu's and wake the cpu that has the earliest timer expiry.
Additionally on arm targets the mem-mapped timers are the wakeup source
for individual cpu's as the local timers are shutdown during some apps
low power modes.

Change-Id: Ic64c759ae9149fde25c86c80cbd91fcb2236ae06
Signed-off-by: Karthik Parsha <kparsha@codeaurora.org>