arm64: stacktrace: Implement arch_bpf_stack_walk() for the BPF JIT

This will be used by bpf_throw() to unwind till the program marked as
exception boundary and run the callback with the stack of the main
program.

This is required for supporting BPF exceptions on ARM64.

Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20240201125225.72796-2-puranjay12@gmail.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>