[RISCV] Map spacemit uarch strings to CPU names in host detection (#207636)

-mcpu/-mtune=native first tries hwprobe;
when that yields no usable CPU model it falls back to the
cpuinfo uarch line. Add spacemit,x60/x100/a100 there.

llvm/lib/TargetParser/Host.cpp

@@ -567,6 +567,9 @@ StringRef sys::detail::getHostCPUNameForRISCV(StringRef ProcCpuinfoContent) {
       .Case("eswin,eic770x", "sifive-p550")
       .Case("sifive,u74-mc", "sifive-u74")
       .Case("sifive,bullet0", "sifive-u74")
+      .Case("spacemit,x60", "spacemit-x60")
+      .Case("spacemit,x100", "spacemit-x100")
+      .Case("spacemit,a100", "spacemit-a100")
       .Default("");
 }