ionic: fix up ionic_if.h kernel-doc issues

All the changes here are whitespace and comments, no code
or definitions changed.  Not all issues were addressed, but
it is much better than it was.  Mostly fixed was a lot
of "Excess union member" and ''rsvd' not described' warnings.
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Link: https://lore.kernel.org/r/20240529000259.25775-8-shannon.nelson@amd.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>