Fixed two bugs: (1) not trapping on unimplemented CSRs (2) MSTATUS.FS initialization

(1) riscy-ooo was mapping all unimplemented CSRs to a benign, user-privilege read-write CSR
    Instead, we now catch this RenameStage and steer it to a trap.
(2) MSTATUS.FS was initialized to 2'b00 (absent/off); should be 2'b01 (present and initial)

src_Core/RISCY_OOO/procs/RV64G_OOO/CommitStage.bsv

@@ -64,7 +64,7 @@ typedef struct {
     Bool stbEmpty;
     Bool stqEmpty;
     Bool tlbNoPendingReq;
-    // CSR info: previlige mode
+    // CSR info: privilege mode
     Bit#(2) prv;
     // inst count
     Data instCount;

src_Core/RISCY_OOO/procs/RV64G_OOO/RenameStage.bsv

@@ -254,7 +254,8 @@ module mkRenameStage#(RenameInput inIfc)(RenameStage);
 	   Bool read_only  = (csr_addr [11:10] == 2'b11);
            Bool write_deny = (writes_csr && read_only);
 	   Bool priv_deny  = (csrf.decodeInfo.prv < csr_addr [9:8]);
-	   csr_access_trap = (write_deny || priv_deny);
+	   Bool unimplemented = (csr_addr == 12'h8ff);    // Added by Bluespec
+	   csr_access_trap = (write_deny || priv_deny || unimplemented);
 	end
 
         // Check WFI trap (using a time-out of 0)

src_Core/RISCY_OOO/procs/lib/ProcTypes.bsv

@@ -1,5 +1,6 @@
 
 // Copyright (c) 2017 Massachusetts Institute of Technology
+// Portions (c) 2020 Bluespec, Inc.
 // 
 // Permission is hereby granted, free of charge, to any person
 // obtaining a copy of this software and associated documentation
@@ -284,6 +285,7 @@ typedef enum {
 
     // CSR that catches all the unimplemented CSRs. To avoid exception on this,
     // make it a user non-standard read/write CSR.
+    // Bluespec: in RenameStage.getTrap(), we force this to be a csr_access_trap
     CSRnone       = 12'h8ff
 } CSR deriving(Bits, Eq, FShow);