mtd: bcm47xxpart: add of_match_table with a new DT binding

This allows using bcm47xxpart parser to find partitions on flash
described in DT using the "brcm,bcm947xx-cfe-partitions" compatible
property. It means this parser doesn't have to be explicitly selected by
a flash driver anymore. It can be used e.g. together with a generic
m25p80 / spi-nor if device is just properly described.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>