dm: i2c: implement gpio-based I2C deblock

The commit implement a gpio-based software deblocking. The code
extract I2C pins description from device tree, switch pins to GPIO
mode, toggle SCL until slave release SDA, send I2C stop and switch
I2C pins back to I2C mode.

Signed-off-by: Alexander Kochetkov <al.kochet@gmail.com>