[Triple] Make loongarch64-*-uefi-* use COFF files by default

UEFI/LoongArch64 always used COFF format.

This pr is inspired by the  Mips's pr llvm#107809.

Author: leecheechen

llvm/lib/TargetParser/Triple.cpp

@@ -946,7 +946,6 @@ static Triple::ObjectFormatType getDefaultFormat(const Triple &T) {
   case Triple::kalimba:
   case Triple::lanai:
   case Triple::loongarch32:
-  case Triple::loongarch64:
   case Triple::m68k:
   case Triple::mips64:
   case Triple::mips64el:
@@ -975,6 +974,11 @@ static Triple::ObjectFormatType getDefaultFormat(const Triple &T) {
   case Triple::xtensa:
     return Triple::ELF;
 
+  case Triple::loongarch64:
+    if (T.isUEFI())
+      return Triple::COFF;
+    return Triple::ELF;
+
   case Triple::mipsel:
     if (T.isOSWindows())
       return Triple::COFF;