hwclock: [m68k] unbreak FTBFS with recent (>= 2.4.18?) kernels

hwclock: [m68k] unbreak FTBFS with recent (>= 2.4.18?) kernels

The old KDGHWCLK ioctl was removed from the Linux kernel quite some
time ago. The kd.c source file of hwclock contains fallback code to
handle this, but the fallback code never could have compiled or was
not fixed along other code changes. The Linux kernel nowadays igno-
res the ioctl entirely so removing it unless provided by the kernel
headers, to keep it working on very old kernels, seems the sensible
thing to do, as the comments say m68k only and deprecated (which is
correct AFAICT).

According to pickaxe on gitweb, it was removed in 2002:
http://git.kernel.org/?p=linux/kernel/git/torvalds/old-2.6-bkcvs.git;a=commit;h=a915e414af5fc541ff62ef0bfec847457ae650bc

Addresses: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=578168
Signed-off-by: Thorsten Glaser <tg@mirbsd.org>
Signed-off-by: Karel Zak <kzak@redhat.com>