misc: tegra-profiler: fix backtraces

misc: tegra-profiler: fix backtraces

Tegra Profiler: fix backtraces from the kernel context.
There should be at least one user space address for such chains.

Bug 1487562

Change-Id: Ibf1f6d78b5f744f397fbcbab54e45f70b6548fbd
Signed-off-by: Igor Nabirushkin <inabirushkin@nvidia.com>
Reviewed-on: http://git-master/r/394493
(cherry picked from commit 8fddf958db67d87f5a3568d9c433d995306dc060)
Reviewed-on: http://git-master/r/395101
Reviewed-by: Automatic_Commit_Validation_User
Tested-by: Maxim Morin <mmorin@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>