image: Correct the OS location code to work on sandbox

A recent change broke the 'bootm' command on sandbox. The root cause is
using a pointer as an address. Conversion from pointer to address needs to
use map_to_sysmem() so that sandbox can do the right thing. The problem was
pre-existing but uncovered by a recent commit.

Fix this. Also move fit_get_end() to the C file to avoid needing to include
mapmem.h (and thus asm/io.h) everywhere.

Fixes: 1fec3c5d (common/image.c: Make boot_get_ramdisk() perform a check for Android images)

Signed-off-by: Simon Glass <sjg@chromium.org>

common/image-fit.c

@@ -851,6 +851,11 @@ static int fit_image_hash_get_ignore(const void *fit, int noffset, int *ignore)
 	return 0;
 }
 
+ulong fit_get_end(const void *fit)
+{
+	return map_to_sysmem((void *)(fit + fdt_totalsize(fit)));
+}
+
 /**
  * fit_set_timestamp - set node timestamp property
  * @fit: pointer to the FIT format image header