ARM: stacktrace: Fix return_address() for CONFIG_FRAME_POINTER

return_address() currently relies on walk_stackframe() setting
frame->lr, but walk_stackframe() never sets this field.

Setting frame->lr from walk_stackframe() would require
walk_stackframe() to unwind one frame beyond the frame being
returned, and to track extra state in struct stackframe.

The value of this is debatable, so this patch modifies
caller_address() to unwind one extra level explicitly and reference
frame->pc instead of frame->lr.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
---
 arch/arm/kernel/return_address.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)