mm: kmemleak: mark kmemleak_init prototype as __init

The kmemleak_init() definition in mm/kmemleak.c is marked __init but its
prototype in include/linux/kmemleak.h is marked __ref since commit
a6186d89c913 ("kmemleak: Mark the early log buffer as __initdata").

This causes a section mismatch which is reported as a warning when
building with clang -Wsection, because kmemleak_init() is declared in
section .ref.text but defined in .init.text.

Fix this by marking kmemleak_init() prototype __init.

Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/kmemleak.h

@@ -25,7 +25,7 @@
 
 #ifdef CONFIG_DEBUG_KMEMLEAK
 
-extern void kmemleak_init(void) __ref;
+extern void kmemleak_init(void) __init;
 extern void kmemleak_alloc(const void *ptr, size_t size, int min_count,
 			   gfp_t gfp) __ref;
 extern void kmemleak_alloc_percpu(const void __percpu *ptr, size_t size,