projects/memtest: Add missing PCF file for icebreaker

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

projects/memtest/data/top-icebreaker.pcf

@@ -0,0 +1,6 @@
+# Clock
+set_io --warn-no-port clk_in 35
+
+# UART
+set_io --warn-no-port uart_rx 6
+set_io --warn-no-port uart_tx 9