fsl_ifc: Change IO accessor based on endianness

IFC IO accressor are set at run time based
on IFC IP registers endianness.IFC node in
DTS file contains information about
endianness.

Signed-off-by: Jaiprakash Singh <b44839@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>
Acked-by: Brian Norris <computersforpeace@gmail.com>