i2c: st: Update i2c timings

The i2c timing values specified in the driver are the minimun values
defined in the I2C specifications. The I2C specification does not
specify any default or maximum values.

Some I2C devices are out of spec, such as the HDMI link of the Toshiba
19AV600 TV, and might not work properly with minimum values.

This patch adds a 10% margin on all the timings in both Normal and Fast modes.

Trial and error method have been used to find the minimum margin necessary to
have the out-of-spec device working, and a security margin has been added.

Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>