ide: remove obsoleted "idebus=" kernel parameter

* Remove obsoleted "idebus=" kernel parameter.

* Remove no longer needed ide_system_bus_speed() and system_bus_clock()
  (together with idebus_parameter and system_bus_speed variables).

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/pci/cmd640.c b/drivers/ide/pci/cmd640.c
index b38a1980..cd1ba14 100644
--- a/drivers/ide/pci/cmd640.c
+++ b/drivers/ide/pci/cmd640.c
@@ -525,12 +525,10 @@
 	u8 setup_count, active_count, recovery_count, recovery_count2, cycle_count;
 	int bus_speed;
 
-	if (cmd640_vlb && ide_vlb_clk)
-		bus_speed = ide_vlb_clk;
-	else if (!cmd640_vlb && ide_pci_clk)
-		bus_speed = ide_pci_clk;
+	if (cmd640_vlb)
+		bus_speed = ide_vlb_clk ? ide_vlb_clk : 50;
 	else
-		bus_speed = system_bus_clock();
+		bus_speed = ide_pci_clk ? ide_pci_clk : 33;
 
 	if (pio_mode > 5)
 		pio_mode = 5;