ARM: dts: omap5-uevm: update optional/unused regulator configurations

ARM: dts: omap5-uevm: update optional/unused regulator configurations

commit c4f0f8c943daffc9c9ea63360e85eec5a49089e6
(ARM: dts: OMAP5: Add Palmas MFD node and regulator nodes)
introduced regulator entries for OMAP5uEVM.

However, The regulator information is based on an older temporary
pre-production board variant and does not reflect production board
750-2628-XXX boards.

The following optional/unused regulators can be updated:

- SMPS9 supplies TWL6040 over VDDA_2v1_AUD. This regulator needs to be
enabled only when audio is active. Since it does not come active by
default, it does not require "always-on" or "boot-on".

- LDO2 and LDO8 do not go to any peripheral or connector on the board.
Further, these unused regulators should have been 2.8V for LDO2 and
3.0V for LDO8. Mark these LDOs as disabled in the dts until needed.

Reported-by: Marc Jüttner <m-juettner@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: J Keerthy <j-keerthy@ti.com>
Acked-by: Benoit Cousson <benoit.cousson@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>