cpufreq/amd-pstate: Do not attempt to clear MSR_AMD_CPPC_ENABLE

cpufreq/amd-pstate: Do not attempt to clear MSR_AMD_CPPC_ENABLE

MSR_AMD_CPPC_ENABLE is a write once register, i.e. attempting to clear
it is futile, it will not take effect. Hence, return if disable (0)
argument is passed to the msr_cppc_enable()

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/20241023102108.5980-3-Dhananjay.Ugwekar@amd.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>