Remove workaround clearning interrpt register
Remove workaround clearning interrpt register

For some reason during dumps for DD2 we were seeing the checkstop
bit pop on this 0xf0001a interrupt attn register but we didnt
see anything with getcfam. I am not longer seeing that bit pop
so I think we are safe to remove this

Change-Id: Idb6b4259e9778165bc09c0b4761472d19015aedc
RTC: 179645
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/46710
Tested-by: Jenkins Server <8e3f934e4c44875bc48d33da3ea13d93ba9a233f@us.ibm.com>
Tested-by: FSP CI Jenkins <aa9e4d9ac7cd25905e9c0dd36d4150516e73dd86@us.ibm.com>
Reviewed-by: Martin Gloff <df0a4963746ae04ab678d064fccc7ee68adfd751@us.ibm.com>
Reviewed-by: Corey V. Swenson <6b585c7446d4a0351ef146912eaabcae3d9a2e28@us.ibm.com>
Tested-by: Jenkins OP Build CI <e610bd72261d3c0a48f1e8ae36832ab00774d426@us.ibm.com>
Tested-by: Jenkins OP HW <0eb0fff262f74a65a832afbcc7b153e391c9a3fd@us.ibm.com>
Reviewed-by: Daniel M. Crowell <912029ca9254ac7b5854e56910561d682e1fa2d0@us.ibm.com>

Over-enthusiastic/hostboot,Over-enthusiastic/hostboot,Over-enthusiastic/hostboot,Over-enthusiastic/hostboot,Over-enthusiastic/hostboot