3 << 16 does not generate the correct mask for bits 16, 17 and 18.
Use the GENMASK macro to generate the correct mask instead.

Fixes: 84fef62d ("nvme: check admin passthru command effects")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>