btrfs: pass struct btrfs_io_geometry to set_io_stripe

Instead of passing three members of 'struct btrfs_io_geometry' into
set_io_stripe() pass a pointer to the whole structure and then get the needed
members out of btrfs_io_geometry.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>