checkpatch: fix __attribute__ matching

In the following code,

union thread_union init_thread_union
	__attribute__((__section__(".data.init_task"))) =
		{ INIT_THREAD_INFO(init_task) };

There is a non-conforming declaration. It should really be like the
following,

union thread_union init_thread_union
	__attribute__((__section__(".data.init_task"))) = {
		INIT_THREAD_INFO(init_task)
};

However, checkpatch doesn't catch this right now because it doesn't
correctly evaluate the "__attribute__".

It is not at all clear that we care what preceeds an assignment style
attribute when we find the open brace.  Relax the test so we do not need
to check the __attribute__.

Reported-by: Daniel Walker <dwalker@fifo99.com>
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>