SAMA5: Add SAMA5 support

Signed-off-by: Bo Shen <voice.shen@atmel.com>
[fix conflicts, not use 9X5's mach type code.]
Signed-off-by: Josh Wu <josh.wu@atmel.com>
SAMA5: add mach type id (for temporary)

Use the same ID as SAM9X5. Do not propagate upstream.
MACB: enable EMAC support for SAMA5EK

Signed-off-by: Bo Shen <voice.shen@atmel.com>
[fix conflict]
GMAC: Enable GMAC on SAMA5EK board
GMAC: Add definition into netdev.h
USB: Enable USB Host
USB: remove unused variable
SPI Flash: Enable serial flash
LCD: Enable uboot boot logo
SAMA5: Add function to distinguish CPU type
LCDC: using has_lcdc() function to avoid error register
NET: using has_emac() and has_gmac to avoid error register
LCDC: using has_lcdc() function to avoid error register
SAMA5: Enable Device Tree support
Bootargs: correct the root partition
MMC: enable MMC support in u-boot
MMC: enable save env into sd card
console: use DBGU as default console
PMC: rework the peripheral clock enable method
LCD: move lcd pin configuration to devices c file
USART: correct the pin of US0 and US2
Clock: clear the clock.c file