x86/sev-es: Replace open-coded hlt-loop with sev_es_terminate()

Replace the halt loop in handle_vc_boot_ghcb() with an
sev_es_terminate(). The HLT gives the system no indication the guest is
unhappy. The termination request will signal there was an error during
VC handling during boot.

  [ bp: Update it to pass the reason set too. ]
Signed-off-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20220317211913.1397427-1-pgonda@google.com

arch/x86/kernel/sev.c

@@ -1982,8 +1982,7 @@ bool __init handle_vc_boot_ghcb(struct pt_regs *regs)
 fail:
 	show_regs(regs);
 
-	while (true)
-		halt();
+	sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ);
 }
 
 /*