sandbox: Add a warm and cold reset driver

Add drivers for sandbox. One can only perform a warm reset (which does
nothing). The other can perform a cold reset or a power reset (the
latter will quit U-Boot). These can be used for testing the reset uclass.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 5da5178..629de25 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -22,6 +22,7 @@
 obj-$(CONFIG_MXS_OCOTP) += mxs_ocotp.o
 obj-$(CONFIG_NS87308) += ns87308.o
 obj-$(CONFIG_PDSP188x) += pdsp188x.o
+obj-$(CONFIG_SANDBOX) += reset_sandbox.o
 ifdef CONFIG_DM_I2C
 obj-$(CONFIG_SANDBOX) += i2c_eeprom_emul.o
 endif