xtensa: implement TIE regset

Put all coprocessors and non-coprocessor TIE state into the REGSET_TIE.
Mark TIE regset with NT_PRFPREG note type.
Reimplement ptrace_getxregs and ptrace_setxregs using REGSET_TIE.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>