Migrate grc blocks from xml to yaml

Convert the blocks using cmdline_converter.py script from
https://gist.githubusercontent.com/haakov/4228ff6a14486641add538483093e86b/raw/c861a840e31182ace2e74f5425e356cb4f8b183a/cmdline_converter.py

Change-Id: Iee5c611a2e100bd2fdf487611a867dc937d8c292
diff --git a/grc/flow_control/gsm_uplink_downlink_splitter.block.yml b/grc/flow_control/gsm_uplink_downlink_splitter.block.yml
new file mode 100644
index 0000000..12d141d
--- /dev/null
+++ b/grc/flow_control/gsm_uplink_downlink_splitter.block.yml
@@ -0,0 +1,23 @@
+# auto-generated by grc.converter
+
+id: gsm_uplink_downlink_splitter
+label: Up/Down-link splitter
+
+inputs:
+-   domain: message
+    id: in
+    optional: true
+
+outputs:
+-   domain: message
+    id: downlink
+    optional: true
+-   domain: message
+    id: uplink
+    optional: true
+
+templates:
+    imports: import grgsm
+    make: grgsm.uplink_downlink_splitter()
+
+file_format: 1