treewide: lib/stack: Fix backtrace

We should never pass the result of __builtin_frame_address(0) to
another function since the compiler is within its rights to pop the
frame to which it points before making the function call, as may be
done for tail calls. Nobody has complained about backtrace(), so
likely all compilations have been inlining backtrace_frame(), not
dropping the frame on the tail call, or nobody is looking at traces.
However, for riscv, when built for EFI, it does drop the frame on the
tail call, and it was noticed. Preemptively fix backtrace() for all
architectures.

Fixes: 52266791 ("lib: backtrace printing")
Acked-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Jones <andrew.jones@linux.dev>