kvm: x86: Expose Intel VPOPCNTDQ feature to guest

Vector population count instructions for dwords and qwords are to be
used in future Intel Xeon & Xeon Phi processors. The bit 14 of
CPUID[level:0x07, ECX] indicates that the new instructions are
supported by a processor.

The spec can be found in the Intel Software Developer Manual (SDM)
or in the Instruction Set Extensions Programming Reference (ISE).

Signed-off-by: Piotr Luc <piotr.luc@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: x86@kernel.org
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>