ARM: dts: omap5: Make uevm as the official board and deprecate sevm support

The uevm is the only official board supported for the OMAP5 soc
in mainline. The existent sevm platform will no more be supported.
Hence cleaning up the board dts file to have only the data
required for uevm.

Renaming the board dts file and adding the following cleanups.

 * There are no devices connected on I2C 2,3,4 buses. So remove
   the pinmux data for the same.

 * OMAP5432 and DDR3 memory is used in the uevm. Temperature polling
   is not supported with DDR3 memories. Because of DDR3 phy limitation
   the voltage change across DVFS and all shadow registers for DVFS on
   DDR3 is not supported. Hence the emif kernel driver is not required,
   so removing the DDR3 device file and emif nodes for uevm.

 * Keypad is not supported on uevm. So remove the device node.

Signed-off-by: Sricharan R <r.sricharan@ti.com>
Signed-off-by: Benoit Cousson <benoit.cousson@linaro.org>