sim: ft32: move arch-specific settings to internal header

There's no need for these settings to be in sim-main.h which is shared
with common/ sim code, so drop the ft32-sim.h include and move it to
the few files that actually need it.

sim/ft32/interp.c

@@ -37,6 +37,8 @@
 
 #include "opcode/ft32.h"
 
+#include "ft32-sim.h"
+
 /*
  * FT32 is a Harvard architecture: RAM and code occupy
  * different address spaces.

sim/ft32/sim-main.h

@@ -24,6 +24,4 @@
 #include "sim-basics.h"
 #include "sim-base.h"
 
-#include "ft32-sim.h"
-
 #endif