scripts/bloat-o-meter: add -p argument

scripts/bloat-o-meter: add -p argument

When doing cross platform development on a machine sometimes it might be
useful to invoke bloat-o-meter for files which haven't been build with the
native toolchain.  In cases when the host nm doesn't support the target
one then a toolchain-specific nm could be used.  Add this ability by
adding the -p allowing invocations as:

./scripts/bloat-o-meter -p riscv64-unknown-linux-gnu- file1.o file2.o

Link: https://lkml.kernel.org/r/20220701113513.1938008-2-nborisov@suse.com
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>