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>

include/ide.h

@@ -54,6 +54,14 @@ void ide_init(void);
 ulong ide_read(int device, ulong blknr, lbaint_t blkcnt, void *buffer);
 ulong ide_write(int device, ulong blknr, lbaint_t blkcnt, const void *buffer);
 
+#ifdef CONFIG_IDE_PREINIT
+int ide_preinit(void);
+#endif
+
+#ifdef CONFIG_IDE_INIT_POSTRESET
+int ide_init_postreset(void);
+#endif
+
 #if defined(CONFIG_OF_IDE_FIXUP)
 int ide_device_present(int dev);
 #endif