x86/hyper-v: Add hyperv Isolation VM check in the cc_platform_has()

x86/hyper-v: Add hyperv Isolation VM check in the cc_platform_has()

Hyper-V provides Isolation VM for confidential computing support and
guest memory is encrypted in it. Places checking cc_platform_has()
with GUEST_MEM_ENCRYPT attr should return "True" in Isolation VM.

Hyper-V Isolation VMs need to adjust the SWIOTLB size just like SEV
guests. Add a hyperv_cc_platform_has() variant which enables that.

Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Acked-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20211213071407.314309-3-ltykernel@gmail.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>