[IA64] Fix CPU freq displayed in /proc/cpuinfo

My patch: git commit=95235ca2 introduced a bug
in IA64 cpuinfo output.

Patch changed the proc_freq from 1HZ resolution to 1KHz resolution, but left
format string unchanged at " %lu.%06lu". Below is the fix.

Thanks to Bjorn for catching this.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>