Fix up some register stuff.

Now you can attach with gdb, and it'll attempt to read a register. That
will fail because the core won't clear debug interrupt. Adding nops
doesn't help this time.

src/target/riscv/opcodes.h

@@ -113,6 +113,10 @@ static uint32_t addi(unsigned int dest, unsigned int src, uint16_t imm)
     MATCH_ADDI;
 }
 
+static uint32_t csrr(unsigned int rd, unsigned int csr) {
+  return (csr << 20) | (rd << 7) | MATCH_CSRRS;
+}
+
 /*
 static uint32_t li(unsigned int dest, uint16_t imm)
 {
@@ -126,10 +130,6 @@ static uint32_t lui(unsigned int dest, uint32_t imm)
     MATCH_LUI;
 }
 
-static uint32_t csrr(unsigned int rd, unsigned int csr) {
-  return (csr << 20) | (rd << 7) | MATCH_CSRRS;
-}
-
 static uint32_t fence_i(void)
 {
   return MATCH_FENCE_I;