ARM: OMAP: Remove loses_context variable from timer platform data

The platform data variable loses_context is used to determine if the timer may
lose its logic state during power transitions and so needs to be restored. This
information is also provided in the HWMOD device attributes for OMAP2+ devices
via the OMAP_TIMER_ALWON flag. When this flag is set the timer will not lose
context. So use the HWMOD device attributes to determine this.

For OMAP1 devices, loses_context is never set and so set the OMAP_TIMER_ALWON
flag for OMAP1 timers to ensure that code is equivalent.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>