I2C: runtime: Fix checks which make legacy suspend to never get called

For devices which are not adapted to runtime PM a call to
pm_runtime_suspended always returns true.

Hence the pm_runtime_suspended checks below prevent legacy
suspend from getting called.

So do a pm_runtime_suspended check only for devices with a
dev_pm_ops populated (which hence do not rely on the legacy
suspend)

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Kevin Hilman <khilman@deeprootsystems.com>