Fix the following sparse warnings:

arch/arm/mach-imx/mach-imx6q.c:60:6: warning: symbol 'imx6q_restart' was not declared. Should it be static?
arch/arm/mach-imx/mach-imx6q.c:223:24: warning: symbol 'imx6q_cpufreq_pdev' 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>