UBUNTU: SAUCE: arm64: Define Cortex-A73 MIDR

UBUNTU: SAUCE: arm64: Define Cortex-A73 MIDR

BugLink: https://bugs.launchpad.net/bugs/1675509
As we're about to introduce a new workaround that is specific to
Cortex-A73, let's define the coresponding MIDR.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
(cherry picked from commit fcd3b9e93c6e735185c2e8187408847dd3295c20
 in the timers/errata-rework branch of
 git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>