ARM: OMAP3+: SmartReflex: use voltage domain name in device attributes

To set sr ntarget values for all volt_domain,
volt_table is retrieved by doing a look_up of 'vdd_name'
field from omap_hwmod but voltage domain pointer does not
belong to omap_hwmod and is not used anywhere else.
As a part of voltage layer and SR Layer clean up volt
pointer is removed from omap_hwmod and added in dev
attributes of SR. The value of the field must match
the voltage domain names for the binding to be effective.

Tested on OMAP3630 SDP, OMAP3530 Beagleboard and
OMAP4430 SDP Board.

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Shweta Gulati <shweta.gulati@ti.com>
Acked by: Nishanth Menon <nm@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Jean Pihet <j-pihet@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>