ARC: disasm: handle ARCv2 case in kprobe get/set functions

Current implementation of get_reg/set_reg implies ARCompact layout
of pt_regs structure. Meanwhile pt_regs structure differs between
ARCompact and ARCv2. Update those functions to handle ARCv2.

Tested-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sergey Matyukevich <sergey.matyukevich@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>