PM / runtime: Update links_count also if !CONFIG_SRCU

PM / runtime: Update links_count also if !CONFIG_SRCU

BugLink: http://bugs.launchpad.net/bugs/1751131
commit 433986c2c265d106d6a8e88006e0131fefc92b7b upstream.

Commit baa8809f6097 (PM / runtime: Optimize the use of device links)
added an invocation of pm_runtime_drop_link() to __device_link_del().
However there are two variants of that function, one for CONFIG_SRCU and
another for !CONFIG_SRCU, and the commit only modified the former.

Fixes: baa8809f6097 (PM / runtime: Optimize the use of device links)
Cc: v4.10+ <stable@vger.kernel.org> # v4.10+
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>