platform/x86: amd-pmc: Avoid reading SMU version at probe time

Currently the SMU version only used to determine whether the SMU supports
reading the idle mask. To speed up startup, move it to the first time
the idle mask is read.

This decreases the startup time from ~28500us to 100us.

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20220411143820.13971-3-mario.limonciello@amd.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>