get_cur_cpufreq support for arm/arm64

Get_cur_cpufreq support is used to get current frequency(in KHz) of the current CPU that the vCPU thread is running on.

• ARM_SMCCC_VENDOR_HYP_KVM_GET_CUR_CPUFREQ_FUNC_ID: 0x86000041

This hypercall uses the SMC32/HVC32 calling convention:

ARM_SMCCC_VENDOR_HYP_KVM_GET_CUR_CPUFREQ_FUNC_ID

Function ID:	(uint32)	0x86000041
Return Values:	(int32) (uint32)	NOT_SUPPORTED(-1) on error, or Frequency in KHz of current CPU that the vCPU thread is running on.
Endianness:		Must be the same endianness as the host.