checkpatch: warn on uses of __constant_<foo> functions

checkpatch: warn on uses of __constant_<foo> functions

Emit a warning when using any of these __constant_<foo> forms:

	__constant_cpu_to_be[x]
	__constant_cpu_to_le[x]
	__constant_be[x]_to_cpu
	__constant_le[x]_to_cpu
	__constant_htons
	__constant_ntohs

Using any of these outside of include/uapi/ isn't preferred as using the
function without __constant_ is identical when the argument is a
constant.

Signed-off-by: Joe Perches <[email protected]>
Cc: Andy Whitcroft <[email protected]>
Cc: Simon Wunderlich <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>