lib/malloc.c: Fix log messages

It is no longer necessary to explicitly add "Warning" in front of
BIOS_WARNING message.

Change-Id: I6e4341555a3b03a531bd94ba5e36cbcadda9c663
Signed-off-by: Elyes Haouas <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/69624
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/lib/malloc.c

@@ -72,7 +72,7 @@ void free(void *ptr)
 		return;
 
 	if (ptr < (void *)&_heap || ptr >= free_mem_end_ptr) {
-		printk(BIOS_WARNING, "Warning - Pointer passed to %s is not "
+		printk(BIOS_WARNING, "Pointer passed to %s is not "
 					"pointing to the heap\n", __func__);
 		return;
 	}