target/armv8_opcodes: use T32 instructions when the PE is in AArch32 state

target/armv8_opcodes: use T32 instructions when the PE is in AArch32 state

As stated in ARM v8-A Architecture Reference Manual (ARM DDI 0487E.a)
in Chapter H4.3 DCC and ITR access modes:
    Writes to EDITR trigger the instruction to be executed if the PE
    is in Debug state:
      - If the PE is in AArch64 state, this is an A64 instruction.
      - If the PE is in AArch32 state, this is a T32 instruction

But in armv8_opcodes specifically in t32_opcodes we were using some
A32 instructions for HLT, LDRx and STRx opcodes.

Using the correct LDRx and STRx opcodes, fixes 16 and 8 bits memory access
when the PE is in AArch32 state.

Change-Id: Ib1acbdd4966297e7b069569bcb8deea3c3993615
Signed-off-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Reviewed-on: http://openocd.zylin.com/5346
Tested-by: jenkins
Reviewed-by: Muhammad Omair Javaid <omair.javaid@linaro.org>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>