Fix calculation of I2C clock for some 85xx chips

Fix calculation of I2C clock for some 85xx chips

Some 85xx chips use CCB as the base clock for the I2C.  Some use CCB/2, and
some use CCB/3.  There is no pattern that can be used to determine which
chips use which frequency, so the only way to determine is to look up the
actual SOC designation and use the right value for that SOC.

Update immap_85xx.h to include the GUTS PORDEVSR2 register.

Signed-off-by: Timur Tabi <timur@freescale.com>