get_sysfs_attr_uncached

Look up the sysfs attribute with name on this.

This function does blocking I/O, and updates the sysfs attributes cache.

Before version 238 the uncached getters would not strip trailing newlines.

Parameters:

this	A Device.
name	Name of the sysfs attribute.

Returns:

The value of the sysfs attribute or null if there is no such attribute. Do not free this string, it is owned by this.