linux/bits.h: simplify GENMASK_INPUT_CHECK()

linux/bits.h: simplify GENMASK_INPUT_CHECK()

In GENMASK_INPUT_CHECK(),

  __builtin_choose_expr(__is_constexpr((l) > (h)), (l) > (h), 0)

is the exact expansion of:

  const_true((l) > (h))

Apply const_true() to simplify GENMASK_INPUT_CHECK().

CC: Linus Torvalds <torvalds@linux-foundation.org>
CC: Rasmus Villemoes <linux@rasmusvillemoes.dk>
CC: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Reviewed-by: Yury Norov <yury.norov@gmail.com>,
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Yury Norov <yury.norov@gmail.com>