Retire the AFS_PTR_FMT macro

Retire the AFS_PTR_FMT macro

Originally '%x' was commonly used as the printf specifier for formatting
pointer values.

Commit 37fc3b01445cd6446f09c476ea2db47fea544b7d introduced the
AFS_PTR_FMT macro to support platform-dependent printf format specifiers
for pointer representation. This macro defined the format specifier as
'%p' for Windows, and '%x' for non-Windows platforms.

Commit 2cf12c43c6a5822212f1d4e42dca7c059a1a9000 changed the printf
pointer format specifier from '%x' to '%p' on non-Windows platforms as
well, so at this point '%p' is the printf pointer format specifier for
all supported platforms.

Since the AFS_PRT_FMT macro is no longer platform-dependent, and all C89
compilers support the '%p' specifier, retire the macro to simplify the
printf format strings.

Change-Id: I0cb13cccbe6a8d0000edd162b623ddcdb74c1cf7
Reviewed-on: https://gerrit.openafs.org/13830
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>