ide: preparations for /proc/ide/hd*/settings rework

After rework settings will be no longer created dynamically
for each device so we need to make some fixups first.

* Use set_[ksettings,unmaskirq]() as a set function for
  ["keepsettings","unmaskirq"] setting.

* Allow writes to ["io_32bit","unmaskirq"] settings also when
  drive->no_[io_32bit,unmask] is set (this is checked later inside
  set_[io_32bit,unmaskirq]() anywyay and keeps consistency with
  the corresponding HDIO_SET_[32BIT,UNMASKINTR] ioctls).

* Use max possible multi sectors value (16) as an allowed max for
  "multcount" setting.  set_multcount() set function checks against
  device's max possbile value anyway and it makes the proc setting
  consistent with the corresponding HDIO_SET_MULTCOUNT ioctl.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide.c b/drivers/ide/ide.c
index 080314e..8e0c9f2 100644
--- a/drivers/ide/ide.c
+++ b/drivers/ide/ide.c
@@ -305,7 +305,7 @@
 	return 0;
 }
 
-static int set_ksettings(ide_drive_t *drive, int arg)
+int set_ksettings(ide_drive_t *drive, int arg)
 {
 	if (arg < 0 || arg > 1)
 		return -EINVAL;
@@ -394,7 +394,7 @@
 	return 0;
 }
 
-static int set_unmaskirq(ide_drive_t *drive, int arg)
+int set_unmaskirq(ide_drive_t *drive, int arg)
 {
 	if (drive->no_unmask)
 		return -EPERM;