checkpatch: find CamelCase definitions of struct/union/enum

Checkpatch doesn't currently find CamelCase definitions of structs, unions
or enums.

Add that ability.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>