nvme: fix merge error due to change of 'make_request_fn' fn type

The type of 'make_request_fn' changed in 5a7bbad2 ("block: remove
support for bio remapping from ->make_request"), but the merge of the
nvme driver didn't take that into account, and as a result the driver
would compile with a warning:

  drivers/block/nvme.c: In function 'nvme_alloc_ns':
  drivers/block/nvme.c:1336:2: warning: passing argument 2 of 'blk_queue_make_request' from incompatible pointer type [enabled by default]
  include/linux/blkdev.h:830:13: note: expected 'void (*)(struct request_queue *, struct bio *)' but argument is of type 'int (*)(struct request_queue *, struct bio *)'

It's benign, but the warning is annoying.

Reported-by: Stephen Rothwell <sfr@canb.auug.org>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>