Workaround for Neoverse N1 erratum 1220197

Workaround for Neoverse N1 erratum 1220197

Neoverse N1 erratum 1220197 is a Cat B erratum [1],
present in older revisions of the Neoverse N1 processor core.
The workaround is to set two bits in the implementation defined
CPUECTLR_EL1 system register, which disables write streaming to the L2.

[1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.pjdoc-466751330-10325/index.html

Change-Id: I9c3373f1b6d67d21ee71b2b80aec5e96826818e8
Signed-off-by: Lauren Wehrmeister <[email protected]>