ioport_{32|64}.c unification.

This patch unifies the code from the ioport_32.c and ioport_64.c files.

Tested and working fine with i386 and x86_64 kernels.
Signed-off-by: Miguel Botón <mboton@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>