cpufreq: qoriq: Add platform dependencies

The Freescale QorIQ clock controller is only present on Freescale E500MC
and Layerscape SoCs.  Add platform dependencies to the QORIQ_CPUFREQ
config symbol, to avoid asking the user about it when configuring a
kernel without E500MC or Layerscape support.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Li Yang <leoyang.li@nxp.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>