scripts/decode_stacktrace.sh: code: preserve alignment

With lines having a code to decode, the alignment was not preserved for
the first line.

With this sample ...

  [   52.238089][   T55] RIP: 0010:__ip_queue_xmit+0x127c/0x1820
  [   52.238401][   T55] Code: c1 83 e0 07 48 c1 e9 03 83 c0 03 (...)

... the script was producing the following output:

  [   52.238089][   T55] RIP: 0010:__ip_queue_xmit (...)
  [ 52.238401][ T55] Code: c1 83 e0 07 48 c1 e9 03 83 c0 03 (...)

That's because scripts/decodecode doesn't preserve the alignment.  No need
to modify it, it is enough to give only the "Code: (...)" part to this
script, and print the prefix without modifications.

With the same sample, we now have:

  [   52.238089][   T55] RIP: 0010:__ip_queue_xmit (...)
  [   52.238401][   T55] Code: c1 83 e0 07 48 c1 e9 03 83 c0 03 (...)

Link: https://lkml.kernel.org/r/20250908-decode_strace_indent-v1-3-28e5e4758080@kernel.org
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Tested-by: Carlos Llamas <cmllamas@google.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: Elliot Berman <quic_eberman@quicinc.com>
Cc: Luca Ceresoli <luca.ceresoli@bootlin.com>
Cc: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

scripts/decode_stacktrace.sh

@@ -242,8 +242,10 @@ debuginfod_get_vmlinux() {
 
 decode_code() {
 	local scripts=`dirname "${BASH_SOURCE[0]}"`
+	local lim="Code: "
 
-	echo "$1" | $scripts/decodecode
+	echo -n "${1%%${lim}*}"
+	echo "${lim}${1##*${lim}}" | $scripts/decodecode
 }
 
 handle_line() {