dss_mgr_start_update() has a loop, of which sole purpose is to find the
manager used for this update. The whole loop is extra, as we already
know the manager.

Remove the loop.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

There's no need to register the vsync ISR and configure the hardware if
the overlay manager is disabled, so this patch adds a check for disabled
managers to the omap_dss_mgr_apply() function.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The mechanism to cache manager and overlay settings and configure them
into the HW registers in VSYNC is meant only for auto-update displays,
as it doesn't make sense (and doesn't work) for manual-update displays.

This patchs adds a check so that we skip the above for manual update
displays.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

Add "enabled" field to struct omap_overlay_manager, which tells if the
output is enabled or not. This will be used in apply.c in the following
patches.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

omap_overlay_manager struct contains enable() and disable() functions.
However, these are only meant to be used from inside omapdss, and thus
it's bad to expose the functions.

This patch adds dss_mgr_enable() and dss_mgr_disable() functions to
apply.c, which handle enabling and disabling the output.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

Create a new file, apply.c, and move code about handling the
apply-mechanism and configuration of the managers and overlays from
manager.c to apply.c.

Not all related code is moved in this patch, but only the core
apply/configure functions. The later patches move rest of the code from
overlay.c and manager.c, adding necessary locking at the same time.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>