According to the device tree specification, the default value for
#size-cells is 1, but fdt_size_cells() was returning 2 if this property
was not present.
This patch also makes fdt_address_cells() and fdt_size_cells() conform
to the behaviour documented in libfdt.h. The defaults are only returned
if fdt_getprop() returns -FDT_ERR_NOTFOUND, otherwise the actual error
is returned.
Signed-off-by: John Clarke <johnc@kirriwa.net>