common: add new boot media kconfig entry

common: add new boot media kconfig entry

Add CONFIG_{SD|NAND|ONENAND|SPI|QSPI|SATA}_BOOT kconfig entries.

SoCs supports loading U-Boot from different medias to DRAM, such as
i.MX6/7 supports loading U-Boot to DRAM from sd/emmc/nand/qspi/spi/sata
and etc. For i.MX, imximage will generate different IVT headers according
to boot medias.

Signed-off-by: Peng Fan <[email protected]>
Cc: Simon Glass <[email protected]>
Cc: Heiko Schocher <[email protected]>
Cc: Joe Hershberger <[email protected]>
Cc: Bin Meng <[email protected]>
Cc: Christophe Ricard <[email protected]>
Cc: Nikita Kiryanov <[email protected]>
Cc: Francois Retief <[email protected]>
Cc: Tom Rini <[email protected]>