staging: mt7621-dts: fix register range of memc node in mt7621.dtsi

The memc node from mt7621.dtsi has incorrect register resource.
Fix it according to the programming guide.

Signed-off-by: Weijie Gao <hackpascal@gmail.com>
Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
Link: https://lore.kernel.org/r/20200109080120.362110-1-gch981213@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>