Fix the following sparse warning:

rch/arm/mach-imx/clk-pllv2.c:232:16: warning: symbol 'clk_pllv2_ops' was not declared. Should it be static?
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>