uboot-imx

ARM: uniphier: add simple eMMC load APIs instead of ROM API

Re-use of routines embedded in the Boot ROM requires a function
pointer table for each SoC.  This is not nice in terms of the
maintainability in a long run.

Implement simple eMMC load APIs that are commonly used for LD11,
LD20, and hopefully future SoCs.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>