arm64: Fix duplicated Kconfig entries

Probably due to rebasing over the lengthy time it took to get the patch
merged commit addea9ef (cpufreq: enable ARM drivers on arm64) added
a duplicate Power management options section.  Add CPUfreq to the CPU
power management section and remove a duplicate include of the main
power section.
Signed-off-by: NMark Brown <broonie@linaro.org>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

arch/arm64/Kconfig

@@ -321,12 +321,6 @@ menu "CPU Power Management"
 
 source "drivers/cpuidle/Kconfig"
 
-endmenu
-
-menu "Power management options"
-
-source "kernel/power/Kconfig"
-
 source "drivers/cpufreq/Kconfig"
 
 endmenu