fbdev: atyfb: Remove unused clock determination

Just below the removed lines par->clk_wr_offset is hard coded to 3 so
there is no use in determining a different clock just to then ignore it
anyway. This also removes the only I/O port use remaining in the driver
allowing it to be built without CONFIG_HAS_IOPORT.

Link: https://lore.kernel.org/all/ZBx5aLo5h546BzBt@intel.com/


Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Helge Deller <deller@gmx.de>