clk: samsung: Remove double assignment of CLK_ARM_CLK in Exynos4 driver
CLK_ARM_CLK ("armclk") clock is provided by cpu-clk subdriver, which is
instantiated after creating all divider clocks from exynos4_div_clks
array. There is no point assigning this id to "div_core2" clock and later
overwrite with proper "armcpu" clock by cpu-clk subdriver.