arm64: dts: broadcom: bcmbca: bcm4908: fix procmon nodename

This fixes:
arch/arm64/boot/dts/broadcom/bcmbca/bcm94908.dtb: syscon@280000: $nodename:0: 'syscon@280000' does not match '^([a-z][a-z0-9\\-]+-bus|bus|localbus|soc|axi|ahb|apb)(@.+)?$'
        From schema: schemas/simple-bus.yaml

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/all/20230228144400.21689-3-zajec5@gmail.com/


Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>