[PATCH 2/7] um: Fix the -Wmissing-prototypes warning for __switch_mm

["Tiwei Bie" <tiwei.btw@antgroup.com>]

The __switch_mm function is defined in the user code, and is called
by the kernel code. It should be declared in a shared header.

Fixes: 4dc706c2f292 ("um: take um_mmu.h to asm/mmu.h, clean asm/mmu_context.h a bit")
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
---
 arch/um/include/asm/mmu.h           | 2 --
 arch/um/include/shared/skas/mm_id.h | 2 ++
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/um/include/asm/mmu.h b/arch/um/include/asm/mmu.h
index a7555e43ed14..f2923c767bb9 100644
--- a/arch/um/include/asm/mmu.h
+++ b/arch/um/include/asm/mmu.h
@@ -14,8 +14,6 @@ typedef struct mm_context {
 	struct uml_arch_mm_context arch;
 } mm_context_t;
 
-extern void __switch_mm(struct mm_id * mm_idp);
-
 /* Avoid tangled inclusion with asm/ldt.h */
 extern long init_new_ldt(struct mm_context *to_mm, struct mm_context *from_mm);
 extern void free_ldt(struct mm_context *mm);
diff --git a/arch/um/include/shared/skas/mm_id.h b/arch/um/include/shared/skas/mm_id.h
index e82e203f5f41..bdfab67174ff 100644
--- a/arch/um/include/shared/skas/mm_id.h
+++ b/arch/um/include/shared/skas/mm_id.h
@@ -15,4 +15,6 @@ struct mm_id {
 	int kill;
 };
 
+extern void __switch_mm(struct mm_id *mm_idp);
+
 #endif
-- 
2.34.1