to -1 and hence cannot be used to identify a timer
   instance. Due to this the following changes were made ...
   a). The API omap_dm_timer_request_specific() is not supported when using
       device-tree, because it uses the device ID to request a specific timer.
       This function will return an error if called when device-tree is present.
       Users of this API should use omap_dm_timer_request_by_cap() instead.
   b). When removing the DMTIMER driver, the timer "id" was used to identify the
       timer instance. The remove function has been modified to use the device
       name instead of the "id".

5. When device-tree is present the platform_data structure will be NULL and so
   check for this.

6. The OMAP timer device tree binding has the following optional parameters ...
   a). ti,timer-alwon  --> Timer is in an always-on power domain
   b). ti,timer-dsp    --> Timer can generate an interrupt to the on-chip DSP
   c). ti,timer-pwm    --> Timer can generate a PWM output
   d). ti,timer-secure --> Timer is reserved on a secure OMAP device
   Search for the above parameters and set the appropriate timer attribute
   flags.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>