use the same va entry point on all armv7 socs

use the same va entry point on all armv7 socs
Similiar changes were made in bitrig by Patrick Wildt.

As part of this change the physical load address for imx and sunxi have
changed.  Any u-boot settings that include it will need to be modified.

imx: 0x10800000 -> 0x10300000
sunxi: 0x40800000 -> 0x40300000

Tested by bmercer, canacar and myself.
ok bmercer@