i2c: designware: Some broken DSTDs use 1MiHz instead of 1MHz

At least the Acer Iconia Tab8 / aka W1-810 uses 1MiHz instead of
1MHz for one of its busses, fix this up to 1MHz instead of failing
the probe of that bus.

This fixes the accelerometer on the Acer Iconia Tab8 not working.

Cc: stable@vger.kernel.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>