We have barebox get its environment out of a "barebox-environment"
partition. The BootROM and first stage bootloader both select partitions
on name not UUID, so we're following suit.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>