mtd: nand: sunxi: rework macros
mtd: nand: sunxi: rework macros

Suffix mask macros with _MSK and add new helper macros to avoid manually
shifting values.

Signed-off-by: Boris Brezillon <4e91513d4f418754031d3d36b3fc73980c40a38c@free-electrons.com>
Signed-off-by: Brian Norris <ac73eed4b8a8c9127255a2696c52b2e7503720b8@gmail.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs