devices/*, unify, add missing instance struct member 'GENstate'

to the generic part of all instance structs, even when actually unused.
see GENstate in "gendefs.h"

src/include/ngspice/mifdefs.h

@@ -54,6 +54,7 @@ struct MIFinstance {
     struct MIFmodel     *MIFmodPtr;       /* backpointer to model */
     struct MIFinstance  *MIFnextInstance; /* pointer to next instance of current model */
     IFuid               MIFname;          /* pointer to character string naming this instance */
+    int                 MIFstates;        /* state info, unused */
 
     int                 num_conn;         /* number of connections on the code model */
     Mif_Conn_Data_t     **conn;           /* array of data structures for each connection */

src/spicelib/devices/ind/inddefs.h

@@ -127,6 +127,7 @@ struct sMUTinstance {
     MUTinstance *MUTnextInstance; /* pointer to next instance of
                                    * current model */
     IFuid MUTname;        /* pointer to character string naming this instance */
+    int MUTstates;        /* state info, unused */
     double MUTcoupling;   /* mutual inductance input by user */
     double MUTfactor;     /* mutual inductance scaled for internal use */
     IFuid MUTindName1;    /* name of coupled inductor 1 */

src/spicelib/devices/txl/txldefs.h

@@ -16,8 +16,8 @@ typedef struct sTXLinstance {
                                              * current model*/
 
     IFuid TXLname;  /* pointer to character string naming this instance */
-    
-        int dimensions; /* may we not need this but ... */
+    int TXLstates;  /* state info, unused */
+
 	int TXLposNode;
 	int TXLnegNode;
 	double TXLlength;