mediatek: cudy: fixes typo for spi and mtd properties

mediatek: cudy: fixes typo for spi and mtd properties

Same as commit 3674689, correct 'buswidth' to 'bus-width'.
Move the nmbm properties outside the partition definition.
Change uppercase to lowercase, add missing read-only flag.

Signed-off-by: Chukun Pan <amadeus@jmu.edu.cn>
(cherry picked from commit ab375a3484db67857450ced461498ad3d7942e05)