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/pci_ep.c b/test/dm/pci_ep.c
index 101f861..a29d00e 100644
--- a/test/dm/pci_ep.c
+++ b/test/dm/pci_ep.c
@@ -5,12 +5,13 @@
 
 #include <common.h>
 #include <dm.h>
+#include <hexdump.h>
+#include <pci_ep.h>
 #include <asm/io.h>
 #include <asm/test.h>
 #include <dm/test.h>
+#include <test/test.h>
 #include <test/ut.h>
-#include <hexdump.h>
-#include <pci_ep.h>
 
 /* Test that sandbox PCI EP works correctly */
 static int dm_test_pci_ep_base(struct unit_test_state *uts)