i2c: designware: Add error checking on init

i2c: designware: Add error checking on init

At present this driver does not check whether it is able to actually
communicate with the I2C controller. It prints a timeout message but still
considers the probe to be successful.

To fix this, add some checking that the init succeeds.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Heiko Schocher <hs@denx.de>