arch-arm: Add HPD bit for TCR_EL2/EL3

This is controlling Hierarchical Permissions for EL3 and for EL2 when
HCR_EL2.E2H = 0.

Change-Id: I9d6615ff4980cc56a28dc32088cf1524155f0fa4
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Ciro Santilli <ciro.santilli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19609
Tested-by: kokoro <noreply+kokoro@google.com>

src/arch/arm/miscregs_types.hh

@@ -502,6 +502,7 @@ namespace ArmISA
         Bitfield<21, 16> t1sz; // EL1
         Bitfield<22> a1; // EL1
         Bitfield<23> epd1; // EL1
+        Bitfield<24> hpd; // EL2/EL3, E2H=0
         Bitfield<25, 24> irgn1; // EL1
         Bitfield<27, 26> orgn1; // EL1
         Bitfield<29, 28> sh1; // EL1