bootstd: Avoid freeing a non-allocated buffer

EFI applications can be very large and thus used to cause boot failures
when malloc() space was exhausted.

A recent changed fixed this by using the kernel_addr_r environment var
as the address of the buffer. However, it still frees the buffer when
the bootflow is discarded.

Fix this by introducing a flag to indicate whether the buffer was
allocated, or not.

Note that kernel_addr_r is not the last word here. It might be better
to use lmb to place images. But there is a lot of refactoring to do
before we can remove the environment variables. The distro scripts rely
on them so it is safe for bootstd to do so too.

Fixes: 6a8c2f9781c bootstd: Avoid allocating memory for the EFI file

Signed-off-by: Simon Glass <sjg@chromium.org>
Reported by: Simon Glass <sjg@chromium.org>
Reported by: Shantur Rathore <i@shantur.com>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Tested-by: Shantur Rathore <i@shantur.com>
diff --git a/boot/bootflow.c b/boot/bootflow.c
index 6922e7e..1ea2966 100644
--- a/boot/bootflow.c
+++ b/boot/bootflow.c
@@ -467,7 +467,8 @@
 	free(bflow->name);
 	free(bflow->subdir);
 	free(bflow->fname);
-	free(bflow->buf);
+	if (!(bflow->flags & BOOTFLOWF_STATIC_BUF))
+		free(bflow->buf);
 	free(bflow->os_name);
 	free(bflow->fdt_fname);
 	free(bflow->bootmeth_priv);