fs/fuse: Remove unneeded kaddr parameter

fuse_dax_mem_range_init() does not need the address or the pfn of the
memory requested in dax_direct_access().  It is only calling direct
access to get the number of pages.

Remove the unused variables and stop requesting the kaddr and pfn from
dax_direct_access().

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Link: https://lore.kernel.org/r/20210525172428.3634316-2-ira.weiny@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>