* mt-tdep.c (mt_register_name): Correct out-of-range logic to
include additional registers.
* mt-tdep.c (mt_gdb_regnums): Add ZI2, ZQ2, Ichannel2,
Iscramb2, Qscramb2, Qchannel2.
(mt_register_name): Likewise.
(mt_copro_register_type): Describe ZI2 and ZQ2.
* mt-tdep.c (mt_gdb_regnums): Define
MT_COPRO_PSEUDOREG_MAC_REGNUM.
(mt_register_name): Use it.
(mt_copro_register_type): Likewise.
(mt_register_type): Likewise.
(mt_pseudo_register_read): Likewise. Read the MAC register, not
the coprocessor register.
(mt_pseudo_register_write): Likewise.