ARM64: perf: add support for frame pointer unwinding in compat mode

ARM64: perf: add support for frame pointer unwinding in compat mode

When profiling a 32-bit application, user space callchain unwinding
using the frame pointer is performed in compat mode. The code is taken
over from the AARCH32 code and adapted to work on AARCH64.

Signed-off-by: Jean Pihet <jean.pihet@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
(cherry picked from commit 23c7d70d55c6d963f225744cd1b996dee68c88d1)
Signed-off-by: Mark Brown <broonie@linaro.org>