checkpatch: warn about memset with swapped arguments

Because the second and third arguments of memset have the same type, it
turns out to be really easy to mix them up.

This bug comes up time after time, so checkpatch should really be checking
for it at patch submission time.

Signed-off-by: Dave Jones <davej@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>