ARM: ux500: Stop registering I2C sub-devices for HREF when DT is enabled

Here we remove all calls to register I2C sub-devices from platform
code when Device Tree is enabled. Instead the I2C driver will parse
the Device Tree for them.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>