checkpatch: do not report nr_static as a static declaration

Ensure we do not report identifiers containing the word static as static
declarations.  For example this should not be reported as an unecessary
assignement of 0:

	long nr_static = 0;

Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>