mm: nommu: refactor debug and warning prints

kenter/kleave/kdebug are wrapper macros to print functions flow and debug
information.  This set was written before pr_devel() was introduced, so it
was controlled by "#if 0" construction.  It is questionable if anyone is
using them [1] now.

This patch removes these macros, converts numerous printk(KERN_WARNING,
...) to use general pr_warn(...) and removes debug print line from
validate_mmap_request() function.

Signed-off-by: Leon Romanovsky <leon@leon.nu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>