initramfs: fix populate_initrd_image() section mismatch

With gcc-4.6.3:

    WARNING: vmlinux.o(.text.unlikely+0x140): Section mismatch in reference from the function populate_initrd_image() to the variable .init.ramfs.info:__initramfs_size
    The function populate_initrd_image() references
    the variable __init __initramfs_size.
    This is often because populate_initrd_image lacks a __init
    annotation or the annotation of __initramfs_size is wrong.

    WARNING: vmlinux.o(.text.unlikely+0x14c): Section mismatch in reference from the function populate_initrd_image() to the function .init.text:unpack_to_rootfs()
    The function populate_initrd_image() references
    the function __init unpack_to_rootfs().
    This is often because populate_initrd_image lacks a __init
    annotation or the annotation of unpack_to_rootfs is wrong.

    WARNING: vmlinux.o(.text.unlikely+0x198): Section mismatch in reference from the function populate_initrd_image() to the function .init.text:xwrite()
    The function populate_initrd_image() references
    the function __init xwrite().
    This is often because populate_initrd_image lacks a __init
    annotation or the annotation of xwrite is wrong.

Indeed, if the compiler decides not to inline populate_initrd_image(), a
warning is generated.

Fix this by adding the missing __init annotations.

Link: http://lkml.kernel.org/r/20190617074340.12779-1-geert@linux-m68k.org
Fixes: 7c184ecd ("initramfs: factor out a helper to populate the initrd image")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

init/initramfs.c

@@ -617,7 +617,7 @@ static inline void clean_rootfs(void)
 #endif /* CONFIG_BLK_DEV_RAM */
 
 #ifdef CONFIG_BLK_DEV_RAM
-static void populate_initrd_image(char *err)
+static void __init populate_initrd_image(char *err)
 {
 	ssize_t written;
 	int fd;
@@ -637,7 +637,7 @@ static void populate_initrd_image(char *err)
 	ksys_close(fd);
 }
 #else
-static void populate_initrd_image(char *err)
+static void __init populate_initrd_image(char *err)
 {
 	printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
 }