lib: Add obvious definition for calloc

The calloc() function is useful in addition to malloc and friends, so
add the obvious definition.

Change-Id: I57a568e323344a97b35014b7b8bec16adc2fd720
Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/51949
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/lib/malloc.c

@@ -1,5 +1,6 @@
-#include <stdlib.h>
 #include <console/console.h>
+#include <stdlib.h>
+#include <string.h>
 
 #if CONFIG(DEBUG_MALLOC)
 #define MALLOCDBG(x...) printk(BIOS_SPEW, x)
@@ -54,6 +55,15 @@ void *malloc(size_t size)
 	return memalign(sizeof(u64), size);
 }
 
+void *calloc(size_t nitems, size_t size)
+{
+	void *p = malloc(nitems * size);
+	if (p)
+		memset(p, 0, nitems * size);
+
+	return p;
+}
+
 void free(void *ptr)
 {
 	if (ptr == NULL)