isdn: whitespace coding style cleanup

isdn source code uses a not-current coding style.

Update the coding style used on a per-line basis
so that git diff -w shows only elided blank lines
at EOF.

Done with emacs and some scripts and some typing.

Built x86 allyesconfig.
No detected change in objdump -d or size.

Signed-off-by: Joe Perches <joe@perches.com>