board: ks2: README: Update to add K2G support

Update the README to add support for K2G EVM. Also
- Add steps on how to use MMC boot
- Fix load address when using CCS
- Update build target to u-boot.bin from u-boot-dtb.bin as all ks2
  platforms uses DT.

Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
1 file changed