x86: HPET force enable for e6xx based systems

As the Soekris net6501 and other e6xx based systems do not have
any ACPI implementation, HPET won't get enabled.
This patch enables HPET on such platforms.

[    0.430149] pci 0000:00:01.0: Force enabled HPET at 0xfed00000
[    0.644838] HPET: 3 timers in total, 0 timers will be used for per-cpu timer

Original patch by Peter Neubauer (http://www.mail-archive.com/soekris-tech@lists.soekris.com/msg06462.html)
slightly modified by Conrad Kostecki <ck@conrad-kostecki.de> and massaged
accoring to Thomas Gleixners <tglx@linutronix.de> by me.

Suggested-by: Conrad Kostecki <ck@conrad-kostecki.de>
Signed-off-by: Eric Sesterhenn <eric.sesterhenn@lsexperts.de>
Cc: Peter Neubauer <pneubauer@bluerwhite.org>
Link: http://lkml.kernel.org/r/5412D3A5.2030909@lsexperts.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>