ARM: ux500: Remove platform specific device registration when DT is enabled

Most devices have now been successfully DT:ed and each supported
platform has its own Device Tree source file. Hence the majority
of the platform specific device registration calls can now be
successfully removed.

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