ARM: mx25: Remove mx25_clocks_init()

mx25_clocks_init() is only used to register the clocks for non-dt platforms.

As mx25 has been converted to a dt-only platform, we can safely remove it.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>