Older compilers either want two extra pairs of curly braces around the
initializer for local variable desc, or they want a single pair of curly
braces with nothing inside.  Because current Linux-kernel practice favors
the latter, this commit makes it so.
Suggested-by: NChris Wilson <chris@chris-wilson.co.uk>
Suggested-by: NJoe Perches <joe@perches.com>
Suggested-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NPaul E. McKenney <paulmck@kernel.org>