i2c: designware: assert reset when error happen at ->probe()

The commit c62ebb3d ("i2c: designware: Add support for an interface clock")
introduced an optional clock while missed correct error handling.
assert reset line back if error happen at ->probe().

Fixes: c62ebb3d ("i2c: designware: Add support for an interface clock")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>