ARM: ti: Update layout for MMC and eMMC (env and dfu)

The problems with the current DFU layout are:
MMC: The space allocated for u-boot is too small for the latest u-boot
     (>750KB). We need to increase it. eMMC uses a much bigger area (2MB).
eMMC: region "u-boot.img.raw" overlaps the environment area and the region
      "spl-os-image.raw".
both: region "spl-os-image.raw" is quite small and can't handle android
      kernels

Fixing this requires growing some regions and moving others.
Care has been taken to leave some room for further growth of
"spl-os-args.raw".
Also the "env" now appears in the dfu so that it's apparent that the
region is not free space that can be used to grow "u-boot.img.raw".
The MLO region is 0x100 sectors wide but the 0x100 are unused in case the
MLO comes too overflow this areas.
The total space allocated for those raw binaries is 16MB, of which 13+MB
are reserved for the kernel image.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>