arc: Fix ARI warning for printf(%p)

arc: Fix ARI warning for printf(%p)

Replace printf ("%p") with printf ("%s", host_address_to_string ()). Printing
host addrss might make sense here because pointers can be null and this would
affect how function behaves.

This particular warning is printed only when option -Wari is passed to
contrib/ari/gdb_ari.sh

gdb/ChangeLog:

	* arc-tdep.c: Fix ARI warning for printf(%p).