mgcoge, mgsuvd: add board specific I2C deblocking mechanism.

As documented in doc/I2C_Edge_Conditions, adding a
board specific deblocking mechanism via CFG_I2C_INIT_BOARD
for the mgcoge and mgsuvd board.

This code was originally written by Keymile in association
with Anatech and Atmel in 1998. The Code toggels the SCL
until the SCA line goes to HIGH (max. 16 times).
And after this, a start condition is sent.

This is another approach to deblock the I2C Bus. The
soft I2C driver actually sends 9 clocks with SDA High,
and then a stop at the end, to deblock the I2C Bus.

Maybe we should use the approach from Keymile as
the new standard?

Signed-off-by: Heiko Schocher <hs@denx.de>