powerpc/85xx: CONFIG_ENABLE_36BIT_PHYS does not depend on CONFIG_PHYS_64BIT

The macro CONFIG_ENABLE_36BIT_PHYS is used to indicate that the given SOC is
capable of 36-bit physical addresses, even if such large addresses are not
used.  On two boards, this macro was enabled only when building a 36-bit
image.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>