The GPIO block on different QorIQ chips could have registers in different
endianess.  Define the property to specify which endian is used by the
hardware.
Signed-off-by: Liu Gang <Gang.Liu@freescale.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Kevin Hilman <khilman@linaro.org>