btrfs: raid56: remove the "_step" infix

btrfs: raid56: remove the "_step" infix

The following functions are introduced as a middle step for bs > ps
support:

- rbio_streip_step_paddr()
- rbio_pstripe_step_paddr()
- rbio_qstripe_step_paddr()
- sector_step_paddr_in_rbio()

As there is already an existing function without the infix, and has a
different parameter list.

But the existing functions have been cleaned up, there is no need to
keep the "_step" infix, just remove it completely.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>