Add hotplug governor

Based on this commit: https://github.com/Voyager2k/android_kernel_asus_tf201/commit/f405d76026e9f4adb6d29e805f8def8a1f1a2c95

	modified:   arch/arm/configs/katkernel_lidpatch_defconfig
	modified:   drivers/cpufreq/Kconfig
	modified:   drivers/cpufreq/Makefile
	new file:   drivers/cpufreq/cpufreq_hotplug.c
	modified:   include/linux/cpufreq.h