[flang] Fixed driver link LIT test for PPC targets. (#134320)

After #131041, the F128 libraries are not linked for PPC targets even
when the driver is built with FLANG_RUNTIME_F128_MATH_LIB.

Author: vzakhari

flang/test/Driver/linker-flags.f90

@@ -2,7 +2,7 @@
 ! invocation. These libraries are added on top of other standard runtime
 ! libraries that the Clang driver will include.
 
-! RUN: %flang -### --target=ppc64le-linux-gnu %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,UNIX,UNIX-F128%f128-lib
+! RUN: %flang -### --target=ppc64le-linux-gnu %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,UNIX,UNIX-F128NONE
 ! RUN: %flang -### --target=aarch64-apple-darwin %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,DARWIN,DARWIN-F128%f128-lib
 ! RUN: %flang -### --target=sparc-sun-solaris2.11 %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,UNIX,SOLARIS-F128%f128-lib
 ! RUN: %flang -### --target=x86_64-unknown-freebsd %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,BSD,BSD-F128%f128-lib