usb: Kconfig: Add Kconfigs entry USB_EHCI_ZYNQ

Add Kconfig entry config option for USB_EHCI_ZYNQ
and update the same to enable for all zynq boards
which supports USB

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/configs/zynq_zc702_defconfig b/configs/zynq_zc702_defconfig
index e1b1fc9..b9e13f2 100644
--- a/configs/zynq_zc702_defconfig
+++ b/configs/zynq_zc702_defconfig
@@ -42,6 +42,8 @@
 CONFIG_DEBUG_UART_CLOCK=50000000
 CONFIG_ZYNQ_QSPI=y
 CONFIG_USB=y
+CONFIG_USB_EHCI_HCD=y
+CONFIG_USB_EHCI=y
 CONFIG_USB_ULPI_VIEWPORT=y
 CONFIG_USB_ULPI=y
 CONFIG_USB_GADGET=y