This device is only used from the device tree, and the startup()
and remove() callbacks are not used anywhere in the kernel, so
retire them and the pdata altogether.

Cc: Samuel Ortiz <sameo@linux.intel.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>