cpufreq/amd-pstate-ut: Convert nominal_freq to khz during comparisons

cpufreq/amd-pstate-ut: Convert nominal_freq to khz during comparisons

cpudata->nominal_freq being in MHz whereas other frequencies being in
KHz breaks the amd-pstate-ut frequency sanity check. This fixes it.

Fixes: e4731baaf294 ("cpufreq: amd-pstate: Fix the inconsistency in max frequency units")
Reported-by: David Arcari <darcari@redhat.com>
Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Link: https://lore.kernel.org/r/20240702081413.5688-2-Dhananjay.Ugwekar@amd.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>