i2c: designware: Fix bogus sda_hold_time due to uninitialized vars

We need to initializes those variables to 0 for platforms that do not
provide ACPI parameters. Otherwise, we set sda_hold_time to random
values, breaking e.g. Galileo and IOT2000 boards.

Fixes: 9d640843

 ("i2c: designware: don't infer timings described by ACPI from clock rate")
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>