[Flang][test] Fix feature spelling (#235068)
The target backend's name is "X86" (Which handles 32 and 64 bits), so
the feature name whether it is available is `x86-registered-target`.
`kinds01.f90` needs `REAL(16)` to work, so also require the
`flang-supports-f128-math` feature.
Fix `kinds02.f90` to make it pass.
Issue discovered by
https://github.com/llvm/llvm-project/pull/216960#discussion_r4342651330
