dfu:core: Find DFU alt setting number by passing its name

New function - dfu_get_alt() - has been added to dfu core. If present, it
returns alt setting's number corresponding to passed name.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
diff --git a/drivers/dfu/dfu.c b/drivers/dfu/dfu.c
index f328735..4ec330c 100644
--- a/drivers/dfu/dfu.c
+++ b/drivers/dfu/dfu.c
@@ -440,3 +440,15 @@
 
 	return NULL;
 }
+
+int dfu_get_alt(char *name)
+{
+	struct dfu_entity *dfu;
+
+	list_for_each_entry(dfu, &dfu_list, list) {
+		if (!strncmp(dfu->name, name, strlen(dfu->name)))
+			return dfu->alt;
+	}
+
+	return -ENODEV;
+}