arm: zynq: Move ZYNQ_SERIAL to Kconfig

Move cadence/zynq serial driver via Kconfig

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/zynq_picozed_defconfig b/configs/zynq_picozed_defconfig
index 0d7b9d6..bbccfa5 100644
--- a/configs/zynq_picozed_defconfig
+++ b/configs/zynq_picozed_defconfig
@@ -36,6 +36,7 @@
 CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_ZYNQ=y
 CONFIG_ZYNQ_GEM=y
+CONFIG_ZYNQ_SERIAL=y
 CONFIG_USB=y
 CONFIG_USB_EHCI_HCD=y
 CONFIG_USB_ULPI_VIEWPORT=y