ipmi: Finally get rid of ipmi_user_t and ipmi_smi_t

All the users have been removed, we can remove the typedefs.
Signed-off-by: Corey Minyard <cminyard@mvista.com>

include/linux/ipmi.h

@@ -27,7 +27,7 @@ struct device;
  * Opaque type for a IPMI message user.  One of these is needed to
  * send and receive messages.
  */
-typedef struct ipmi_user *ipmi_user_t;
+struct ipmi_user;
 
 /*
  * Stuff coming from the receive interface comes as one of these.

include/linux/ipmi_smi.h

@@ -28,7 +28,7 @@ struct device;
  */
 
 /* Structure for the low-level drivers. */
-typedef struct ipmi_smi *ipmi_smi_t;
+struct ipmi_smi;
 
 /*
  * Messages to/from the lower layer.  The smi interface will take one