aarch64: Update feature RAS system registers

This patch:
+ updates RAS feature system registers with new RAS 1.1 regs.
+ extends RAS/RAS 1.1 support for all architecture levels of Armv8-A.

Please note that early Armv8-A architectures do not officially support RAS
extension.

Rationale of the patch:
To ease development so that user-friendly RAS system registers operands can be
used. Certain use cases require developers to enable only more generic
architecture (e.g. -march=armv8-a) during system development. Users must use
RAS extension registers bearing in mind that system they use must support it.

The RAS (Reliability, Availability, Serviceability) extension is a
system-level extension that defines a number of system registers.

RAS 1.1 (FEAT_RASv1p1) introduces five new system registers:
ERXPFGCTL_EL1, ERXPFGCDN_EL1, ERXMISC2_EL1, ERXMISC3_EL1 and
ERXPFGF_EL1.

For details see [0].

[0] https://developer.arm.com/docs/ddi0595/i/