Neoverse N1: Introduce workaround for Neoverse N1 erratum 1315703

Neoverse N1: Introduce workaround for Neoverse N1 erratum 1315703

Neoverse N1 erratum 1315703 is a Cat A (rare) erratum [1], present in
older revisions of the Neoverse N1 processor core.
The workaround is to set a bit in the implementation defined CPUACTLR2_EL1
system register, which will disable the load-bypass-store feature.

[1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.pjdocpjdoc-466751330-1032/index.html

Change-Id: I5c708dbe0efa4daa0bcb6bd9622c5efe19c03af9
Signed-off-by: Andre Przywara <[email protected]>