ARM: dts: omap4-panda-common: Add watchdog timers for IPU and DSP

The watchdog timers have been added for the IPU and DSP remoteproc
devices on all the OMAP4-based Panda boards. The following timers
are used as the watchdog timers,
	DSP : GPT6
	IPU : GPT9 & GPT11 (one for each Cortex-M3 core)

The MPU-side drivers will use this data to initialize the watchdog
timers, and listen for any watchdog triggers. The BIOS-side code
needs to configure and refresh these timers properly to not throw
a watchdog error.

These timers can be changed or removed as per the system integration
needs, alongside appropriate equivalent changes on the firmware side.

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