fpga: make Quartus slightly happier with regards to QSF files

fpga/v1.qsf

@@ -1,4 +1,5 @@
-set_global_assignment -name SOURCE_TCL_SCRIPT_FILE "max80.qsf"
+set_global_assignment -name SOURCE_TCL_SCRIPT_FILE max80.qsf
+set_global_assignment -name TOP_LEVEL_ENTITY max80
 set_global_assignment -name SOURCE_FILE v1.pins
 set_global_assignment -name VERILOG_MACRO MAX80_V1
-set_global_assignment -name SOURCE_FILE max80-v1.cof
+set_global_assignment -name SOURCE_FILE "max80-v1.cof"

fpga/v2.qsf

@@ -1,4 +1,5 @@
-set_global_assignment -name SOURCE_TCL_SCRIPT_FILE "max80.qsf"
+set_global_assignment -name SOURCE_TCL_SCRIPT_FILE max80.qsf
+set_global_assignment -name TOP_LEVEL_ENTITY max80
 set_global_assignment -name SOURCE_FILE v2.pins
 set_global_assignment -name VERILOG_MACRO MAX80_V2
-set_global_assignment -name SOURCE_FILE max80-v2.cof
+set_global_assignment -name SOURCE_FILE "max80-v2.cof"