i2c: proof of concept i2c register reading.

Toy driver to map the i2c registers and then read and display the
value of the I2C_REV register.
i2c: clock configuration
padconf: add am335x registers

Change-Id: I5ea50a243f3847d5cdea291caae0fb4be93b2f20
i2c: pinmux and bring module out of reset

Use padconf to setup the i2c pins. Follow the TRM suggestions
for bringing up the i2c module from reset.
i2c: quick and dirty eeprom reader

Partial implementation of omap_i2c_read() and the skeleton of
part of an eeprom driver. This isn't production ready, but it
shows that the initialization code works.

Tested on the BBB. Will try the xM soon.

Change-Id: I48e9fe836772a34a2e9d09e4a0b82a2bd7b24182