configs: sandbox: activate env in ext4 support

Activate ENV in EXT4 support in sandbox.

The sandbox behavior don't change; the default environment with
the nowhere backend (CONFIG_ENV_IS_NOWHERE)is still used:
the weak function env_get_location() return ENVL_NOWHERE for priority 0.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>

board/sandbox/sandbox.c

@@ -7,6 +7,7 @@
 #include <cpu_func.h>
 #include <cros_ec.h>
 #include <dm.h>
+#include <env_internal.h>
 #include <init.h>
 #include <led.h>
 #include <os.h>
@@ -44,6 +45,20 @@ unsigned long timer_read_counter(void)
 }
 #endif
 
+/* specific order for sandbox: nowhere is the first value, used by default */
+static enum env_location env_locations[] = {
+	ENVL_NOWHERE,
+	ENVL_EXT4,
+};
+
+enum env_location env_get_location(enum env_operation op, int prio)
+{
+	if (prio >= ARRAY_SIZE(env_locations))
+		return ENVL_UNKNOWN;
+
+	return env_locations[prio];
+}
+
 int dram_init(void)
 {
 	gd->ram_size = CONFIG_SYS_SDRAM_SIZE;