mtd: spi-nor: fix nor->addr_width when its value configured from SFDP does not match the actual width
IS25LP256 gets BFPT_DWORD1_ADDRESS_BYTES_3_ONLY from BFPT table for
address width. But in actual fact the flash can support 4-byte address.
Use a post bfpt fixup hook to overwrite the address width advertised by
the BFPT.