ARM: ux500: select CPU_FREQ_TABLE where needed

The ux500 platform requires CPU_FREQ_TABLE support to be enabled
for its CPU_FREQ implementations, so automatically select that
when CPU_FREQ is enabled.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
[Rebased due to missing other patches in the stack]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>