tcg: add TCG_TARGET_TLB_DISPLACEMENT_BITS

This will be used to size the TLB when more than 8 MMU modes are
used by the target. Limitations come from the limited size of
the immediate fields (which sometimes, as in the case of Aarch64,
extend to instructions that shift the immediate).

Backports commit 006f8638c62bca2b0caf609485f47fa5e14d8a3c from qemu

qemu/tcg/aarch64/tcg-target.h

@@ -14,6 +14,7 @@
 #define TCG_TARGET_AARCH64 1
 
 #define TCG_TARGET_INSN_UNIT_SIZE  4
+#define TCG_TARGET_TLB_DISPLACEMENT_BITS 24
 #undef TCG_TARGET_STACK_GROWSUP
 
 typedef enum {

qemu/tcg/arm/tcg-target.h

@@ -27,6 +27,7 @@
 
 #undef TCG_TARGET_STACK_GROWSUP
 #define TCG_TARGET_INSN_UNIT_SIZE 4
+#define TCG_TARGET_TLB_DISPLACEMENT_BITS 16
 
 typedef enum {
     TCG_REG_R0 = 0,

qemu/tcg/i386/tcg-target.h

@@ -25,6 +25,7 @@
 #define TCG_TARGET_I386 1
 
 #define TCG_TARGET_INSN_UNIT_SIZE  1
+#define TCG_TARGET_TLB_DISPLACEMENT_BITS 31
 
 #ifdef __x86_64__
 # define TCG_TARGET_REG_BITS  64

qemu/tcg/mips/tcg-target.h

@@ -27,6 +27,7 @@
 #define TCG_TARGET_MIPS 1
 
 #define TCG_TARGET_INSN_UNIT_SIZE 4
+#define TCG_TARGET_TLB_DISPLACEMENT_BITS 16
 #define TCG_TARGET_NB_REGS 32
 
 typedef enum {

qemu/tcg/ppc/tcg-target.h

@@ -32,6 +32,7 @@
 
 #define TCG_TARGET_NB_REGS 32
 #define TCG_TARGET_INSN_UNIT_SIZE 4
+#define TCG_TARGET_TLB_DISPLACEMENT_BITS 16
 
 typedef enum {
     TCG_REG_R0,  TCG_REG_R1,  TCG_REG_R2,  TCG_REG_R3,

qemu/tcg/s390/tcg-target.h

@@ -25,6 +25,7 @@
 #define TCG_TARGET_S390 1
 
 #define TCG_TARGET_INSN_UNIT_SIZE 2
+#define TCG_TARGET_TLB_DISPLACEMENT_BITS 19
 
 typedef enum TCGReg {
     TCG_REG_R0 = 0,

qemu/tcg/sparc/tcg-target.h

@@ -27,6 +27,7 @@
 #define TCG_TARGET_REG_BITS 64
 
 #define TCG_TARGET_INSN_UNIT_SIZE 4
+#define TCG_TARGET_TLB_DISPLACEMENT_BITS 32
 #define TCG_TARGET_NB_REGS 32
 
 typedef enum {