Redo shield, removing FPGA

Don't have the FPGA on the shield, just have it be a board that plugs
into the FPGA.

Don't mind the component and footprint choices yet, I still need to
figure out exactly which parts to use.

hw/efinix_shield/fpga.kicad_sch

@@ -0,0 +1,10 @@
+(kicad_sch (version 20211123) (generator eeschema)
+
+  (uuid 7c3cb301-6908-40e7-8dcb-36d01477708c)
+
+  (paper "A4")
+
+  (lib_symbols
+  )
+
+)