Pyra DT: reworked to define I2C clock frequencies and pinmux only once and independent of list of clients

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Pyra DT: use OMAP5_IOPAD() macro for all pinmux settings

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>