i2c: designware_i2c: Don't warn if no reset controller

At present if CONFIG_RESET is not enabled, this code shows a warning:

  designware_i2c_ofdata_to_platdata() i2c_designware_pci i2c2@16,0:
	Can't get reset: -524

Avoid this by checking if reset is supported, first.

Fixes: 622597de ("i2c: designware: add reset ctrl to driver")
Signed-off-by: Simon Glass <sjg@chromium.org>