clk: rockchip: fix coding style for clk-cpu.c

Fix the issue reported by checkpatch:
ERROR: space prohibited before that ',' (ctx:WxW)
+               writel(clksel->val , cpuclk->reg_base + clksel->reg);

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>