presence: Complete current method type functions

Fill in the necessary function to return the associated policy access
pointer for the tach and gpio presence sensor methods.

Tested:
    Method type functions return correct sensor pointer by type
    Method type functions throw exception for missing params

Change-Id: I947fe6a3f9458ef07bb2ecc9540604d9845a276f
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
1 file changed