kernel-doc: handle arrays with arithmetic expressions as initializers

In a different approach here's a patch that handles the special case of
composite arithmetic expressions in array size initializers.  With it,
prior to pushing the split strings on the @first_arg array, I split the
keywords before the array name as before and then keep the array name along
with the subscript expression as a single whole element which gets pushed
last.  In this manner, kernel-doc produces correct output without removing
whitespaces which makes the array subscripts unreadable in the docs.

Signed-off-by: Borislav Petkov <bbpetkov@yahoo.de>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>