IVF_PQ failed to query on GPU if 'nbits' doesn't equal to 8

[shengjun1985]

Please state your issue using the following template and, most importantly, in English.

Describe the bug
IVF_PQ failed to query on GPU if 'nbits' doesn't equal to 8

Steps/Code to reproduce behavior
(1) create a collection (dim = 128)
(2) insert vectors
(3) create index (ivf_pq, nlist = 2048, m = 16, nbit = 9)
(4) query

Expected behavior

Method of installation

• Docker/cpu
• Docker/gpu
• Build from source

Environment details

• Hardware/Software conditions (OS, CPU, GPU, Memory)

• Milvus version (master or released version)
  1.0.0

Configuration file
Settings you made in server_config.yaml or milvus.yaml

paste-file-content-here

Screenshots
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Additional context
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