ARM: dts: aspeed: Update spi alias in Facebook AST2500 Common dtsi

Set FMC controller to "spi0" in ast2500-facebook-netbmc-common.dtsi so
the spi bus is consistent with the flash labels defined in flash layout.

Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20230803230324.731268-2-rentao.bupt@gmail.com


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