uboot-imx

omap: add basic SPL support

- Provide alternate implementations of board_init_f()
  board_init_r() for OMAP spl.
- Provide linker script
- Initialize global data
- Add serial console support
- Update CONFIG_SYS_TEXT_BASE to allow for SPL's bss and move
  it to board config header from config.mk

Signed-off-by: Aneesh V <aneesh@ti.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>