[PATCH] spl: add support for custom boot method names

[Michael Walle]

Am 2022-01-13 16:22, schrieb Heiko Thiery:
> Currently the names MMC1, MMC2 and MMC2_2 are output in the SPL. To
> achieve more userbility here the name of the boot source can be 
> returned.
> E.g. for "MMC1" -> "eMMC" or "MMC2" -> "SD card".
> 
> Signed-off-by: Heiko Thiery <heiko.thiery at gmail.com>

Tested-by: Michael Walle <michael at walle.cc>