[ARM] Add Cortex-M55 Support for clang and llvm

This patch upstreams support for the ARM Armv8.1m cpu Cortex-M55.

In detail adding support for:

 - mcpu option in clang
 - Arm Target Features in clang
 - llvm Arm TargetParser definitions

details of the CPU can be found here:
https://developer.arm.com/ip-products/processors/cortex-m/cortex-m55

Reviewers: chill

Reviewed By: chill

Subscribers: dmgreen, kristof.beyls, hiraditya, cfe-commits,
llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D74966
diff --git a/llvm/lib/Support/Host.cpp b/llvm/lib/Support/Host.cpp
index 1597e6f..9b9d60e 100644
--- a/llvm/lib/Support/Host.cpp
+++ b/llvm/lib/Support/Host.cpp
@@ -192,6 +192,7 @@
             .Case("0xc20", "cortex-m0")
             .Case("0xc23", "cortex-m3")
             .Case("0xc24", "cortex-m4")
+            .Case("0xd22", "cortex-m55")
             .Case("0xd02", "cortex-a34")
             .Case("0xd04", "cortex-a35")
             .Case("0xd03", "cortex-a53")