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/dma.c b/test/dm/dma.c
index 317ed4f..1cdc813 100644
--- a/test/dm/dma.c
+++ b/test/dm/dma.c
@@ -11,6 +11,7 @@
 #include <malloc.h>
 #include <dm/test.h>
 #include <dma.h>
+#include <test/test.h>
 #include <test/ut.h>
 
 static int dm_test_dma_m2m(struct unit_test_state *uts)