mm/early_ioremap: add explicit #include of asm/early_ioremap.h

Commit 6b0f68e3 ("mm: add utility for early copy from unmapped ram")
introduces a function copy_from_early_mem() into mm/early_ioremap.c
which itself calls early_memremap()/early_memunmap().  However, since
early_memunmap() has not been declared yet at this point in the .c file,
nor by any explicitly included header files, we are depending on a
transitive include of asm/early_ioremap.h to declare it, which is
fragile.

So instead, include this header explicitly.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/early_ioremap.c

@@ -15,6 +15,7 @@
 #include <linux/mm.h>
 #include <linux/vmalloc.h>
 #include <asm/fixmap.h>
+#include <asm/early_ioremap.h>
 
 #ifdef CONFIG_MMU
 static int early_ioremap_debug __initdata;