ARM: dts: dra7-ipu-dsp-common: Add timers to IPU and DSP nodes

ARM: dts: dra7-ipu-dsp-common: Add timers to IPU and DSP nodes

The BIOS System Tick timers have been added for all the IPU and
DSP remoteproc devices in the DRA7 SoC family. The data is added
to the two common dra7-ipu-dsp-common and dra74-ipu-dsp-common
dtsi files that are included by all the desired board files. The
following timers are chosen, as per the timers used on the current
firmware images:
        IPU2: GPTimer 3
        IPU1: GPTimer 11
        DSP1: GPTimer 5
        DSP2: GPTimer 6

The timers are optional, but are mandatory to support advanced device
management features such as power management and watchdog support.
The above are added to successfully boot and execute firmware images
configured with the respective timers, images that use internal
processor subsystem timers are not affected. The timers can be
changed or removed as per the system integration needs, if needed.

Each of the IPUs has two Cortex-M4 processors, and is currently
expected to be running in SMP-mode, so only a single timer suffices
to provide the BIOS tick timer. An additional timer should be added
for the second processor in IPU if it were to be run in non-SMP mode.
The timer value also needs to be unique from the ones used by other
processors so that they can be run simultaneously.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>