ARM: ux500: Provide device enumeration number suffix for SMSC911x

First Ethernet device has a ".0" appended onto the device name.
Since on a non-DT boot the ethernet will be named "smsc911x.0"
and since the clocks are not converted to device tree these
names need to be matched when providing the name from
auxdata.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
[edited commit message]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>