clk: exynos5410: Update cpufreq KFC related clocks for exynos5410

cpufreq driver for exynos5410 is not a platform driver, hence we
cannot currently pass the clock names through a device tree
node. Instead, we need to make them available through a global
alias. cpufreq driver for exynos5410 requires four clocks -
'mout_kpll', 'mout_kfc' and 'sclk_kpll'. 'mout_kpll', 'mout_kfc'
and 'sclk_kpll' are now defined with an alias.