ARM: kgdb: ignore breakpoint instructions from user mode

Avoid conflicts with user mode usage of the same instructions, as with
Clang -ftrapv.

Change-Id: I12d1c6d8f94376bfd2503cb0be843d7e478fb6ea
Signed-off-by: Todd Poynor <toddpoynor@google.com>
Git-commit: c4715194082e79c7fb8e82e0f373f27a01ed3676
Git-Repo: https://android.googlesource.com/kernel/common.git


Signed-off-by: Ian Maund <imaund@codeaurora.org>