dm: fix ofnode_read_addr/size_cells()

In the case of the live tree ofnode_read_addr_cells() and
ofnode_read_size_cells() return the #address-cells and #size-cells defined
in the parent node. With the patch the same is done for a non-live tree.

The only consumer of these functions is currently the CFI flash driver.

This patch fixes the incorrect parsing of the device tree leading to
'saveenv' failing on qemu_arm64_defconfig.

For testing qemu-system-aarch64 has to be called with

    -drive if=pflash,format=raw,index=1,file=envstore.img

to provide the flash memory. envstore.img must be 64 MiB large.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Stefan Roese <sr@denx.de>