platforms/xilinx: add a tcl create to rebuild gthe4 IP

platform/xilinx/wr_gtp_phy/xilinx-ip/gthe4/create-gth.tcl

+# Regeneration of the gthe4 IP
+# Open a vivado project with an ZynqUS+ target
+# in the TCL console
+#  source ./create-gth.tcl
+# Check the differences
+# Cleanup (comment out unused gthe3, gtye3 and gtye4 instantiations; this
+#  avoids adding extra unused files)
+# Copy the files
+
+set module_name {gtwizard_ultrascale_2}
+
+create_ip -name gtwizard_ultrascale -vendor xilinx.com -library ip -version 1.7 -module_name $module_name -dir .
+
+set_property CONFIG.preset {GTH-Gigabit_Ethernet} [get_ips $module_name]
+
+set_property -dict [list \
+  CONFIG.RX_BUFFER_MODE {0} \
+  CONFIG.TX_BUFFER_MODE {0} \
+  CONFIG.RX_SLIDE_MODE {PCS} \
+  CONFIG.LOCATE_IN_SYSTEM_IBERT_CORE {EXAMPLE_DESIGN} \
+  CONFIG.LOCATE_RX_USER_CLOCKING {CORE} \
+  CONFIG.LOCATE_TX_USER_CLOCKING {CORE} \
+] [get_ips $module_name]
+
+generate_target all [get_ips $module_name]
+catch { config_ip_cache -export [get_ips $module_name] }
+export_ip_user_files -of_objects [get_ips $module_name] -no_script -sync -force -quiet
+create_ip_run [get_ips $module_name]
+
+unset module_name