x86: Add macros to clear and set I/O bits

The clrsetbits_...() macros are useful for working with memory mapped I/O.
But they do not work with I/O space, as used on x86 machines.

Add some macros to provide similar features for I/O.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>