[U-Boot] [PATCH] mx6sabresd: Add fastboot support

[Shawn Guo]

On Mon, Jan 29, 2018 at 11:11:57AM -0200, Fabio Estevam wrote:
> From: Fabio Estevam <fabio.estevam at nxp.com>
> 
> fastboot tool is a convenient way to flash the eMMC, so
> add support for it.
> 
> Examples of usages:
> 
> On the mx6sabresd:
> 
> => fastboot 0
> 
> On the Linux PC connected via USB:
> 
> $ sudo fastboot getvar bootloader-version -i 0x0525
> bootloader-version: U-Boot 2018.01-00550-g7517cfe
> finished. total time: 0.000s
> 
> $ sudo fastboot reboot -i 0x0525
> 
> (this causes the mx6sabresd to reboot)
> 
> Signed-off-by: Fabio Estevam <fabio.estevam at nxp.com>

Tested-by: Shawn Guo <shawn.guo at linaro.org>