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/legacy/ali14xx.c b/drivers/ide/legacy/ali14xx.c
index 90c65cf..052125f 100644
--- a/drivers/ide/legacy/ali14xx.c
+++ b/drivers/ide/legacy/ali14xx.c
@@ -116,7 +116,7 @@
 	int time1, time2;
 	u8 param1, param2, param3, param4;
 	unsigned long flags;
-	int bus_speed = ide_vlb_clk ? ide_vlb_clk : system_bus_clock();
+	int bus_speed = ide_vlb_clk ? ide_vlb_clk : 50;
 
 	/* calculate timing, according to PIO mode */
 	time1 = ide_pio_cycle_time(drive, pio);