Replaced function of_property_read_u8 to of_property_read_u32

I found the bug "of_property_read_u8" always return 0, which is not solved in v3.8 branch. As we can avoid it by using "of_property_read_u32" instead, I replace them.

Signed-off-by: shyeon.kim <shyeon.kim@scipi.net>