x86/sev: Add internal header guards

All headers need guards ifdeffery.

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://patch.msgid.link/20251204124809.31783-3-bp@kernel.org

Author: bp3tk0v

arch/x86/coco/sev/internal.h

@@ -1,4 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __X86_COCO_SEV_INTERNAL_H__
+#define __X86_COCO_SEV_INTERNAL_H__
 
 #define DR7_RESET_VALUE        0x400
 
@@ -85,3 +87,4 @@ enum es_result sev_es_ghcb_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt
 u64 get_hv_features(void);
 
 const struct snp_cpuid_table *snp_cpuid_get_table(void);
+#endif /* __X86_COCO_SEV_INTERNAL_H__ */