checkpatch: add ability to --fix unnecessary blank lines around braces

There's a --strict test for these blank lines.

Add the ability to automatically remove them with --fix.

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>