reset: implement a reset test

This adds a sandbox reset implementation (provider), a test client
device, instantiates them both from Sandbox's DT, and adds a DM test
that excercises everything.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/test/dm/Makefile b/test/dm/Makefile
index 9eaf04b..cad3374 100644
--- a/test/dm/Makefile
+++ b/test/dm/Makefile
@@ -27,6 +27,7 @@
 obj-$(CONFIG_RAM) += ram.o
 obj-y += regmap.o
 obj-$(CONFIG_REMOTEPROC) += remoteproc.o
+obj-$(CONFIG_DM_RESET) += reset.o
 obj-$(CONFIG_SYSRESET) += sysreset.o
 obj-$(CONFIG_DM_RTC) += rtc.o
 obj-$(CONFIG_DM_SPI_FLASH) += sf.o