Sparse reports a warning at device_links_read_unlock()

warning:  warning: context imbalance in device_links_read_unlock()
	 - unexpected unlock

The root cause is the missing annotation at device_links_read_unlock()
Add the missing __releases(&device_links_srcu) annotation
Signed-off-by: NJules Irenge <jbi.octave@gmail.com>
Link: https://lore.kernel.org/r/20200214204741.94112-20-jbi.octave@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>