Make access to sysfs lock-free

[ms-hujia]

This PR aims to remove the lock used in SysFsAccessInterface. The lock is not necessary and should be avoided based on below facts:

1. Simultaneous read/write operations against the same sysfs instance are atomic by design.
2. For simultaneous read/write operations to different sysfs instances belonging to the same device, it's the driver's responsibility to ensure the data consistency. If a lock is needed at user-level, this usually indicates defect at device driver.
3. According to the spec of Level Zero, most get/set function has the note The implementation of this function should be lock-free..