[CPUFREQ] Longhaul - Add ignore_latency option

Some laptops with VIA C3 processor, CLE266 chipset and
AMI BIOS have incorrect latency values in FADT table. These
laptops seems to be C3 capable, but latency values are to
big: 101 for C2 and 1017 for C3. This option will allow
user to skip C3 latency test but not C3 address test. AMI
BIOS is setting C3 address to correct value in DSDT table.

Signed-off-by: Rafa Bilski <rafalbilski@interia.pl>
Signed-off-by: Dave Jones <davej@redhat.com>