nvme: ignore subnqn for ADATA SX6000LNP

The ADATA SX6000LNP NVMe SSDs have the same subnqn and, due to this, a
system with more than one of these SSDs will only have one usable.

[ 0.942706] nvme nvme1: ignoring ctrl due to duplicate subnqn (nqn.2018-05.com.example:nvme:nvm-subsystem-OUI00E04C).
[ 0.943017] nvme nvme1: Removing after probe failure status: -22

02:00.0 Non-Volatile memory controller [0108]: Realtek Semiconductor Co., Ltd. Device [10ec:5762] (rev 01)
71:00.0 Non-Volatile memory controller [0108]: Realtek Semiconductor Co., Ltd. Device [10ec:5762] (rev 01)

There are no firmware updates available from the vendor, unfortunately.
Applying the NVME_QUIRK_IGNORE_DEV_SUBNQN quirk for these SSDs resolves
the issue, and they all work after this patch:

/dev/nvme0n1     2J1120050420         ADATA SX6000LNP [...]
/dev/nvme1n1     2J1120050540         ADATA SX6000LNP [...]

Signed-off-by: Misha Nasledov <misha@nasledov.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>