Revert "x86/sev: Expose sev_es_ghcb_hv_call() for use by HyperV"

This reverts commit 007faec0.

Now that hyperv does its own protocol negotiation:

  49d6a3c0 ("x86/Hyper-V: Add SEV negotiate protocol support in Isolation VM")

revert this exposure of the sev_es_ghcb_hv_call() helper.

Cc: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by：Tianyu Lan <tiala@microsoft.com>
Link: https://lore.kernel.org/r/20220614014553.1915929-1-ltykernel@gmail.com