The original dts of CV1800B has a weird memory length as it
contains reserved memory for coprocessor. Make this area a
separate node so it can get the real memory length.

Link: https://lore.kernel.org/r/IA1PR20MB49531F274753B04A5547DB59BB052@IA1PR20MB4953.namprd20.prod.outlook.comSigned-off-by: Inochi Amaoto <inochiama@outlook.com>
Signed-off-by: Chen Wang <unicorn_wang@outlook.com>