acpi-cpufreq: Fix nominal_freq units to KHz in get_max_boost_ratio()

acpi-cpufreq: Fix nominal_freq units to KHz in get_max_boost_ratio()

commit 083466754596 ("cpufreq: ACPI: Fix max-frequency computation")
modified get_max_boost_ratio() to return the nominal_freq advertised
in the _CPC object. This was for the purposes of computing the maximum
frequency. The frequencies advertised in _CPC objects are in
MHz. However, cpufreq expects the frequency to be in KHz. Since the
nominal_freq returned by get_max_boost_ratio() was not in KHz but
instead in MHz,the cpuinfo_max_frequency that was computed using this
nominal_freq was incorrect and an invalid value which resulted in
cpufreq reporting the P0 frequency as the cpuinfo_max_freq.

Fix this by converting the nominal_freq to KHz before returning the
same from get_max_boost_ratio().

Reported-by: Manu Bretelle <chantr4@gmail.com>
Closes: https://lore.kernel.org/lkml/aDaB63tDvbdcV0cg@HQ-GR2X1W2P57/
Fixes: 083466754596 ("cpufreq: ACPI: Fix max-frequency computation")
Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Cc: 6.14+ <stable@vger.kernel.org> # 6.14+
Link: https://patch.msgid.link/20250529085143.709-1-gautham.shenoy@amd.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>