Fix throttle procedure & MSS attribute clean up

Change-Id: I7b545b65aaf9cdfea08ab2c5142898f5c971a74b
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/23486
Tested-by: Jenkins Server
Tested-by: Hostboot CI
Reviewed-by: Louis Stermole <[email protected]>
Reviewed-by: JACOB L. HARVEY <[email protected]>
Reviewed-by: Daniel M. Crowell <[email protected]>
Reviewed-by: Brian R. Silver <[email protected]>
Reviewed-by: Jennifer A. Stofer <[email protected]>
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/69763
Tested-by: Jenkins Server <[email protected]>
Tested-by: FSP CI Jenkins <[email protected]>
Reviewed-by: Sachin Gupta <[email protected]>