i2c: designware: Use the i2c_mark_adapter_suspended/resumed() helpers

Use the i2c_mark_adapter_suspended/resumed() i2c-core helpers and rely
on the i2c-core's suspended checking instead of using DIY code.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>