[RISCV][NFC] Add a newline when using --print-enabled-extensions (#98425)

The `--print-enabled-extensions` has been introduced in the
#98207 , but it seems to be
missing a newline in the end.

Author: sunshaoce

llvm/lib/TargetParser/RISCVISAInfo.cpp

@@ -151,7 +151,7 @@ void RISCVISAInfo::printEnabledExtensions(
 
   unsigned XLen = IsRV64 ? 64 : 32;
   if (auto ISAString = RISCVISAInfo::createFromExtMap(XLen, FullExtMap))
-    outs() << "\nISA String: " << ISAString.get()->toString();
+    outs() << "\nISA String: " << ISAString.get()->toString() << "\n";
 }
 
 static bool stripExperimentalPrefix(StringRef &Ext) {

llvm/unittests/TargetParser/RISCVISAInfoTest.cpp

@@ -1081,7 +1081,8 @@ R"(Extensions enabled for the given RISC-V target
 Experimental extensions
     zicfilp              0.4       'Zicfilp' (Landing pad)
 
-ISA String: rv64i2p1_zicfilp0p4_zicsr2p0)";
+ISA String: rv64i2p1_zicfilp0p4_zicsr2p0
+)";
   // clang-format on
 
   StringMap<StringRef> DescMap;