Remove two unused fields from gdbarch

When I converted gdbarch to use the registry, I forgot to remove the
two fields that were used to implement the previous approach.  This
patch removes them.  Tested by rebuilding.
diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index 46baca9..04fcc92 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -48,10 +48,6 @@ struct gdbarch
   gdbarch_tdep_up tdep;
   gdbarch_dump_tdep_ftype *dump_tdep = nullptr;
 
-  /* per-architecture data-pointers.  */
-  unsigned nr_data = 0;
-  void **data = nullptr;
-
   int short_bit = 2*TARGET_CHAR_BIT;
   int int_bit = 4*TARGET_CHAR_BIT;
   int long_bit = 4*TARGET_CHAR_BIT;
diff --git a/gdb/gdbarch.py b/gdb/gdbarch.py
index 7dc7938..3ebc359 100755
--- a/gdb/gdbarch.py
+++ b/gdb/gdbarch.py
@@ -289,10 +289,6 @@
     print("  gdbarch_tdep_up tdep;", file=f)
     print("  gdbarch_dump_tdep_ftype *dump_tdep = nullptr;", file=f)
     print(file=f)
-    print("  /* per-architecture data-pointers.  */", file=f)
-    print("  unsigned nr_data = 0;", file=f)
-    print("  void **data = nullptr;", file=f)
-    print(file=f)
     for c in filter(not_info, components):
         if isinstance(c, Function):
             print(f"  gdbarch_{c.name}_ftype *", file=f, end="")