headers/deps: libata: Optimize <linux/libata.h> dependencies, remove <linux/sched.h> inclusion

          --------------------------------------------------------------------
          | Combined, preprocessed C code size of header, without line markers,
          | with comments stripped:
          -------------------------
  before: | #include <linux/libata.h>               | LOC: 25,761 | headers:  469
   after: | #include <linux/libata.h>               | LOC: 25,351 | headers:  463

Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 97c0b93..1015008 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -22,7 +22,6 @@
 #include <scsi/scsi_host.h>
 #include <linux/acpi.h>
 #include <linux/cdrom.h>
-#include <linux/sched.h>
 #include <linux/async.h>
 
 /*