ARM: imx: remove unused imx6q_clock_map_io()

imx6q_clock_map_io() becomes an empty function since imx6q clock driver
is moved to common clock framework.  It's used nowhere now.  Remove it.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/mach-imx/common.h

@@ -139,7 +139,6 @@ extern void imx_gpc_init(void);
 extern void imx_gpc_pre_suspend(void);
 extern void imx_gpc_post_resume(void);
 extern int imx6q_set_lpm(enum mxc_cpu_pwr_mode mode);
-extern void imx6q_clock_map_io(void);
 
 extern void imx_cpu_die(unsigned int cpu);