fix bug: IVFPQ of raft/cuvs does not require redundant check (facebookresearch#4241)

Summary:
The IVFPQ of raft/cuvs does not require pq length check for Faiss' original implementation. This check make IVFPQ support limited parameters than raft/cuvs in vain.
The check of supported PQ code length here
https://github.com/facebookresearch/faiss/blob/ede2c99137efed18150839c07796e0856faec383/faiss/gpu/impl/IVFPQ.cu#L80-L102

is for Faiss' original CUDA implementation. Raft/cuvs support more choices.

The wiki of faiss also describe the limitation (https://github.com/facebookresearch/faiss/wiki/Faiss-on-the-GPU#limitations), which needs to be update, too. Raft/cuvs is not limited to those choices.

Pull Request resolved: facebookresearch#4241

Reviewed By: bshethmeta, gtwang01

Differential Revision: D72200376

Pulled By: mnorris11

fbshipit-source-id: 2b81e822a397f3ab4a7c691e38be0186535d129d

Author: weiwch

faiss/gpu/GpuIndexIVFPQ.cu

@@ -566,17 +566,13 @@ void GpuIndexIVFPQ::verifyPQSettings_() const {
                     "Bits per code must be 8 (passed %d)",
                     bitsPerCode_);
         }
-    }
-
-    // The number of bytes per encoded vector must be one we support
-    FAISS_THROW_IF_NOT_FMT(
-            ivfpqConfig_.interleavedLayout ||
-                    IVFPQ::isSupportedPQCodeLength(subQuantizers_),
-            "Number of bytes per encoded vector / sub-quantizers (%d) "
-            "is not supported",
-            subQuantizers_);
-
-    if (!should_use_cuvs(config_)) {
+        // The number of bytes per encoded vector must be one we support
+        FAISS_THROW_IF_NOT_FMT(
+                ivfpqConfig_.interleavedLayout ||
+                        IVFPQ::isSupportedPQCodeLength(subQuantizers_),
+                "Number of bytes per encoded vector / sub-quantizers (%d) "
+                "is not supported",
+                subQuantizers_);
         // Sub-quantizers must evenly divide dimensions available
         FAISS_THROW_IF_NOT_FMT(
                 this->d % subQuantizers_ == 0,