PM / AVS: SmartReflex: use volt_nominal as the search key for NVALUE

SmartReflex NVALUES are stored per voltage in DTB and in platform data,
therefore voltage is the most right search key to retrieve corresponding
NVALUE. Additional benefit of this decision is the folowing:
"sr_efuse_offs" can be removed from "struct omap_volt_data",
this can be done as a part of cleanup of mach-omap2.

Signed-off-by: Andrii Tseglytskyi <andrii.tseglytskyi@ti.com>
PM / AVS: SmartReflex: retrieve omap_sr* from pdata on driver remove

struct omap_sr* is stored in platform data during SmartReflex driver
probe. Therefore on driver remove it can be directly accessed,
benefit of such solution - is removing of one _sr_lookup()
function call.

Signed-off-by: Andrii Tseglytskyi <andrii.tseglytskyi@ti.com>
PM / AVS: SmartReflex: delay probe if class is not initialized

SmartReflex driver can't work without if SmartReflex class
is not initialized. Patch adds sanity check of availability of
SmartReflex class, if class is not yet initialized - probe
will be deferred.

Signed-off-by: Andrii Tseglytskyi <andrii.tseglytskyi@ti.com>
PM / AVS: Add init from DTB for SmartReflex

SmartReflex SoC specific data can be placed in Device Tree.
Patch adds posiibility to use it, it updates init sequence of
SmartReflex driver:
- SmartReflex speific data is retrieved from DTB
- NVALUES are read from EFUSES during driver probe

To keep backward compatibility, SmartReflex can be initialized
in the usual way - using platform_device and platform_data, which are
defined in sr_device.c. This path is used if DTB is not defined for
corresponding SmartReflex.

Signed-off-by: Andrii Tseglytskyi <andrii.tseglytskyi@ti.com>
ARM: dts: OMAP4430: add device node for AVS

Patch adds AVS device node definition for MPU voltagedomain
and corresponding bindings to kernel documentation.

Signed-off-by: Andrii Tseglytskyi <andrii.tseglytskyi@ti.com>
HACK: PM / AVS: force enable and dump SmartReflex register on boot

Signed-off-by: Andrii Tseglytskyi <andrii.tseglytskyi@ti.com>