x86, microcode, AMD: Add a vendor-specific exit function

This will be used to do cleanup work before the driver exits.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h
index 2421507..4ebe157 100644
--- a/arch/x86/include/asm/microcode.h
+++ b/arch/x86/include/asm/microcode.h
@@ -48,6 +48,7 @@
 
 #ifdef CONFIG_MICROCODE_AMD
 extern struct microcode_ops * __init init_amd_microcode(void);
+extern void __exit exit_amd_microcode(void);
 
 static inline void get_ucode_data(void *to, const u8 *from, size_t n)
 {
@@ -59,6 +60,7 @@
 {
 	return NULL;
 }
+static inline void __exit exit_amd_microcode(void) {}
 #endif
 
 #endif /* _ASM_X86_MICROCODE_H */