add configuration schema for usb port

Add configuration schema for usb port defining properties such as baud
rate, data parity etc. This schema will be used by phosphor-modbus
service to connect to modbus rtu devices.

Tested: Schema validation passes.

Change-Id: Ib8ca83bb81cd367c9ecdba44cb3802f154a91bb6
Signed-off-by: Jagpal Singh Gill <paligill@gmail.com>
diff --git a/schemas/meson.build b/schemas/meson.build
index 12a4c07..e68d526 100644
--- a/schemas/meson.build
+++ b/schemas/meson.build
@@ -18,5 +18,6 @@
     'satellite_controller.json',
     'stepwise.json',
     'topology.json',
+    'usb_port.json',
     'virtual_sensor.json',
 ]