split mpc8xx hooks from cmd_ide.c

move most of mpc8xx hooks from cmd_ide.c into ide_preinit() and newly created
ide_init_postreset() (invoked after calling ide_reset after ide_preinit),
some cleanup to make checkpatch happy, enable IDE init hooks in configs of
affected boards.
confusingly, these hooks are used by more than just mpc8xx-based boards, and
therefore are placed in arch/ppc/lib/

note: checkpatch still emits warnings about using volatile

Signed-off-by: Pavel Herrmann <morpheus.ibis@gmail.com>
diff --git a/include/configs/RRvision.h b/include/configs/RRvision.h
index 671d521..e2b22f0 100644
--- a/include/configs/RRvision.h
+++ b/include/configs/RRvision.h
@@ -329,6 +329,7 @@
  *-----------------------------------------------------------------------
  */
 
+#define CONFIG_IDE_PREINIT	1	/* Use preinit IDE hook */
 #define	CONFIG_IDE_8xx_PCCARD	1	/* Use IDE with PC Card	Adapter	*/
 
 #undef	CONFIG_IDE_8xx_DIRECT		/* Direct IDE    not supported	*/