ARM: OMAP2+: Cleanup omap_timer_capability_dev_attr usage

The omap_timer_capability_dev_attr data was used to supply instance
specific capabilities (like always-on, PWM functionality or ability
to interrupt DSP cores) for legacy non-DT devices. These capabilities
are now provided through device-tree properties. The legacy device
support has been cleaned up in commit 8d39ff3d ("ARM: OMAP2+:
Remove unused legacy code for timer") and this data is therefore
no longer needed. So, cleanup the structure and all the associated
data in various hwmod data files.

While at this, remove the stale header in hwmod data files that
already do not have any timer capability data.

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