dm: core: Drop header files from dm/test.h

These header file should not be included in other header files. Remove
them and add to each individual file. Add test/test.h to test/ui.h since
that is a reasonable place.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/dm/i2s.c b/test/dm/i2s.c
index 49ebc35..7a017be 100644
--- a/test/dm/i2s.c
+++ b/test/dm/i2s.c
@@ -7,9 +7,10 @@
 #include <common.h>
 #include <dm.h>
 #include <i2s.h>
+#include <asm/test.h>
 #include <dm/test.h>
+#include <test/test.h>
 #include <test/ut.h>
-#include <asm/test.h>
 
 /* Basic test of the i2s codec uclass */
 static int dm_test_i2s(struct unit_test_state *uts)