dpkg: fix configuration issue for mips64

CQID: 431771

configure cannot determine the proper cpu, os, or
architecture for mips64, and possibly other arch's,
because of faulty code added to Arch.pm in the latest
release from upstream.  We remove that code.

Signed-off-by: Joe Slater <jslater@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>