ARM: dts: aspeed: wedge40: Update FMC flash0 label

Update FMC flash0's label to "spi0.0" so it's consistent with all the
other Facebook OpenBMC platforms.

Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
Link: https://lore.kernel.org/r/20200824182955.7988-2-rentao.bupt@gmail.com


Signed-off-by: Joel Stanley <joel@jms.id.au>