rsa: don't use malloc.h in rsa-sign.c
stdlib.h is the header for malloc since at least c89/c90.
There is no system malloc.h on OpenBSD and trying to use malloc.h here
falls back to the U-Boot malloc.h breaking the build of qemu_arm64.
Fixes: 336d4615f8 ("dm: core: Create a new header file for 'compat' features")
Signed-off-by: Jonathan Gray <jsg@jsg.id.au>
diff --git a/lib/rsa/rsa-sign.c b/lib/rsa/rsa-sign.c
index 580c744..621ddc4 100644
--- a/lib/rsa/rsa-sign.c
+++ b/lib/rsa/rsa-sign.c
@@ -4,7 +4,7 @@
*/
#include "mkimage.h"
-#include <malloc.h>
+#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <image.h>