util: resource: Allocate storage for attribute data at set interest

util: resource: Allocate storage for attribute data at set interest

This introduces the new way to using attribute value. Instead of
allocate memory for each attribute value by driver-self, memory is
allocated when client sets interest for each attribute. This can
prevent from unnecessary memory allocation by deferring until it is
really required.

Change-Id: Ie6d47db4c6735510a0e784f8c254705c2c176b25
Signed-off-by: Dongwoo Lee <dwoo08.lee@samsung.com>