ARM: ux500: Provide a means to obtain the SMSC9115 clock when DT is enabled

Device Tree names devices differently to how some frameworks expect
them. Until we can move a platform over to the new way of obtaining
resources, we have to use the OF_DEV_AUXDATA() macros to craft a
device name which can be used in searches during allocation time.

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