phy: add a NO-OP phy driver

This driver is used to stub PHY operations in a driver (USB, SATA).
This is useful when the 'client' driver (USB, SATA, ...) uses the PHY
framework and there is no actual PHY harwdare to drive.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile
index 6ce96d2..ab56c46 100644
--- a/drivers/phy/Makefile
+++ b/drivers/phy/Makefile
@@ -6,5 +6,6 @@
 #
 
 obj-$(CONFIG_$(SPL_)PHY) += phy-uclass.o
+obj-$(CONFIG_$(SPL_)NOP_PHY) += nop-phy.o
 obj-$(CONFIG_PHY_SANDBOX) += sandbox-phy.o
 obj-$(CONFIG_$(SPL_)PIPE3_PHY) += ti-pipe3-phy.o