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>

configs/sandbox_defconfig

@@ -172,6 +172,8 @@ CONFIG_CONSOLE_TRUETYPE_CANTORAONE=y
 CONFIG_VIDEO_SANDBOX_SDL=y
 CONFIG_FS_CBFS=y
 CONFIG_FS_CRAMFS=y
+CONFIG_PHY=y
+CONFIG_PHY_SANDBOX=y
 CONFIG_CMD_DHRYSTONE=y
 CONFIG_TPM=y
 CONFIG_LZ4=y

configs/sandbox_noblk_defconfig

@@ -174,6 +174,8 @@ CONFIG_CONSOLE_TRUETYPE_CANTORAONE=y
 CONFIG_VIDEO_SANDBOX_SDL=y
 CONFIG_FS_CBFS=y
 CONFIG_FS_CRAMFS=y
+CONFIG_PHY=y
+CONFIG_PHY_SANDBOX=y
 CONFIG_CMD_DHRYSTONE=y
 CONFIG_TPM=y
 CONFIG_LZ4=y

configs/sandbox_spl_defconfig

@@ -178,6 +178,8 @@ CONFIG_CONSOLE_TRUETYPE_CANTORAONE=y
 CONFIG_VIDEO_SANDBOX_SDL=y
 CONFIG_FS_CBFS=y
 CONFIG_FS_CRAMFS=y
+CONFIG_PHY=y
+CONFIG_PHY_SANDBOX=y
 CONFIG_CMD_DHRYSTONE=y
 CONFIG_TPM=y
 CONFIG_LZ4=y