ARM: OMAP: Add function to request timer by node

Add a function so that OMAP dmtimers can be requested by device-tree
node. This allows for devices, such as the internal DSP, or drivers,
such as PWM, to reference a specific dmtimer node via the device-tree.

Given that there are several APIs available for requesting dmtimers
(by ID, by capability or by node) consolidate the code for all these
functions into a single helper function that can be used by these
request functions.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
ARM: OMAP: Force dmtimer restore if context loss is not detectable

When booting with device-tree the function pointer for detecting context
loss is not populated. Ideally, the pm_runtime framework should be
enhanced to allow a means for reporting context/state loss and we could
avoid populating such function pointers altogether. In the interim until
a generic non-device specific solution is in place, force a restore of
the dmtimer when enabling the timer. Also add a warning during probe to
warn that context loss cannot be detected.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Merge branch 'omap-dmtimer-for-v3.10' into omap-daily-testing