scripts/decode_stacktrace.sh: symbol: avoid trailing whitespaces

A few patches slightly improving the output generated by
decode_stacktrace.sh.


This patch (of 3):

Lines having a symbol to decode might not always have info after this
symbol. It means ${info_str} might not be set, but it will always be
printed after a space, causing trailing whitespaces.

That's a detail, but when the output is opened with an editor marking
these trailing whitespaces, that's a bit disturbing. It is easy to remove
them by printing this variable with a space only if it is set.

While at it, do the same with ${module} and print everything in one line.

Link: https://lkml.kernel.org/r/20250908-decode_strace_indent-v1-0-28e5e4758080@kernel.org
Link: https://lkml.kernel.org/r/20250908-decode_strace_indent-v1-1-28e5e4758080@kernel.org
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Reviewed-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Cc: Carlos Llamas <cmllamas@google.com>
Cc: Elliot Berman <quic_eberman@quicinc.com>
Cc: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>