get_freqtbl support for arm/arm64

Allows guest to query the frequency(in KHz) table of the current CPU that the vCPU thread is running on.

• ARM_SMCCC_VENDOR_HYP_KVM_GET_CPUFREQ_TBL_FUNC_ID: 0x86000043

This hypercall uses the SMC32/HVC32 calling convention:

ARM_SMCCC_VENDOR_HYP_KVM_GET_CPUFREQ_TBL_FUNC_ID

Function ID:	(uint32)	0x86000043
Arguments:	(uint32)	index of the current CPU's frequency table
Return Values:	(int32) (uint32)	NOT_SUPPORTED(-1) on error, or Frequency table entry of requested index in KHz of current CPU(r1)
Endianness:		Must be the same endianness as the host.