serial: pxa: use kconfig for serial configuration

Migrate the PXA serial driver to be configured via Kconfig.

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Reviewed-by: Marek Vasut <marex@denx.de>
diff --git a/configs/h2200_defconfig b/configs/h2200_defconfig
index c1b359e..a47159a 100644
--- a/configs/h2200_defconfig
+++ b/configs/h2200_defconfig
@@ -24,3 +24,4 @@
 # CONFIG_CMD_NFS is not set
 CONFIG_CMD_PING=y
 # CONFIG_CMD_MISC is not set
+CONFIG_PXA_SERIAL=y