arm64: Add MIDR encoding for Arm Cortex-A77

Add Arm Cortex-A77's part-number so we can match against its MIDR_EL1.

Change-Id: I3f394338fe49d4fd553b6d5388fc1962a8d049ef
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Patch-mainline: linux-arm-kernel @ 11/14/19, 14:59
[sramana@codeaurora.org: Resolve trivial merge conflicts]
Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>