ARM: OMAP: Add DMTIMER capability variable to represent timer features

ARM: OMAP: Add DMTIMER capability variable to represent timer features

Although the OMAP timers share a common hardware design, there are some
differences between the timer instances in a given device. For example, a timer
maybe in a power domain that can be powered-of, so can lose its logic state and
need restoring where as another may be in power domain that is always be on.
Another example, is a timer may support different clock sources to drive the
timer. This information is passed to the dmtimer via the following platform data
structure.

struct dmtimer_platform_data {
	int (*set_timer_src)(struct platform_device *pdev, int source);
	int timer_ip_version;
	u32 needs_manual_reset:1;
	bool loses_context;
	int (*get_context_loss_count)(struct device *dev);
};

The above structure uses multiple variables to represent the timer features.
HWMOD also stores the timer capabilities using a bit-mask that represents the
features supported. By using the same format for representing the timer
features in the platform data as used by HWMOD, we can ...

1. Use the flags defined in the plat/dmtimer.h to represent the features
   supported.
2. For devices using HWMOD, we can retrieve the features supported from HWMOD.
3. Eventually, simplify the platform data structure to be ...

struct dmtimer_platform_data {
	int (*set_timer_src)(struct platform_device *pdev, int source);
	u32 timer_capability;
}

Another benefit from doing this, is that it will simplify the migration of the
dmtimer driver to device-tree. For example, in the current OMAP2+ timer code the
"loses_context" variable is configured at runtime by calling an architecture
specific function. For device tree this creates a problem, because we would need
to call the architecture specific function from within the dmtimer driver.
However, such attributes do not need to be queried at runtime and we can look up
the attributes via HWMOD or device-tree.

This changes a new "capability" variable to the platform data and timer
structure so we can start removing and simplifying the platform data structure.

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