Retire pccard(4)

pccard has been declared obsolete for a long time and also the
support has been removed but the man page still exists. It mentions
being scheduled to be removed before 13.0 but it still exists in the
tree.

[Extracted from review D53434]

Reviewed by: emaste
Fixes: 31b35400c ("pccard: Remove more of the PC Card infrastructure")

(cherry picked from commit 5b9fba1cb0d84ee297908ec4d575c33cf1f68ad5)