drm/amd/pm: use pm_runtime_get_if_active for debugfs getters

drm/amd/pm: use pm_runtime_get_if_active for debugfs getters

Don't wake up the GPU for reading pm values. Instead, take a runtime
powermanagement ref when trying to read it if and only if the GPU is
already awake.

This avoids spurious wake ups (eg: from applets).

We use pm_runtime_get_if_in_active because we care about "is the GPU awake?"
not about "is the GPU awake and something else prevents suspend?".

Tested-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Kenneth Feng <kenneth.feng@amd.com>
Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>