coresight: etm4x: Remove the state_needs_restore flag

coresight: etm4x: Remove the state_needs_restore flag

When the restore flow is invoked, it means no error occurred during the
save phase. Otherwise, if any errors happened while saving the context,
the function would return an error and abort the suspend sequence.

Therefore, the state_needs_restore flag is unnecessary. The save and
restore functions are changed to check two conditions:

1) The global flag pm_save_enable is SELF_HOSTED mode;
2) The device is in active mode (non DISABLED).

Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Tested-by: James Clark <james.clark@linaro.org>
Signed-off-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20251111-arm_coresight_power_management_fix-v6-8-f55553b6c8b3@arm.com