dm: test: Add tests for the generic PHY uclass

Those tests check:
- the ability for a phy-user to get a phy based on its name or its index
- the ability of a phy device (provider) to manage multiple ports
- the ability to perform operations on the phy (init,deinit,on,off)
- the behavior of the uclass when optional operations are not implemented

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
index 0a74920..75f459d 100644
--- a/drivers/phy/Kconfig
+++ b/drivers/phy/Kconfig
@@ -33,4 +33,12 @@
 	  compatible as possible with the equivalent framework found in the
 	  linux kernel.
 
+config PHY_SANDBOX
+	bool "Sandbox PHY support"
+	depends on SANDBOX
+	depends on PHY
+	help
+	  This select a dummy sandbox PHY driver. It used only to implement
+	  the unit tests for the phy framework
+
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