If statements don't need multiple parentheses around tested comparisons
like "if ((foo == bar))".

An == comparison maybe a sign of an intended assignment, so emit a
slightly different message if so.
Signed-off-by: NJoe Perches <joe@perches.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Andy Whitcroft <apw@canonical.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>