nvme-pci: fix CMB sysfs file removal in reset path

nvme-pci: fix CMB sysfs file removal in reset path

[ Upstream commit 1c78f7735b2bdd0afbe5d14c5c8b6d8d381b6f13 ]

Currently we create the sysfs entry even if we fail mapping
it. In that case, the unmapping will not remove the sysfs created
file. There is no good reason to create a sysfs entry for a non
working CMB and show his characteristics.

Fixes: f63572dff ("nvme: unmap CMB and remove sysfs file in reset path")
Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Stephen Bates <sbates@raithlin.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>