checkpatch: extend CamelCase types and ignore existing CamelCase uses in a patch

Extend the CamelCase words found to include structure members.

In https://lkml.org/lkml/2013/9/3/318 Sarah Sharp (mostly) wrote:

"In general, if checkpatch.pl complains about a variable a patch
introduces that's CamelCase, you should pay attention to it.  Otherwise,
[] ignore it."

So, if checking a patch, scan the original patched file if it's available
and add any preexisting CamelCase types so reuses do not generate
CamelCase messages.

That also means Andrew's not so cruelly spurned anymore.
https://lkml.org/lkml/2013/2/22/426



Signed-off-by: Joe Perches <joe@perches.com>
Suggested-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>