greybus: core: add device prefix to error messages

Use dev_err and dev_warn where appropriate and remove now unused pr_fmt
defines.

Testing Done:
Tested on DB3.5 with the generic bridge firmware on APB2.

Signed-off-by: Johan Hovold <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/greybus/debugfs.c

···
  * Released under the GPLv2 only.
  */
 
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
 #include <linux/debugfs.h>
 
 #include "greybus.h"

drivers/staging/greybus/hd.c

···
  * Released under the GPLv2 only.
  */
 
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
 #include <linux/kernel.h>
 #include <linux/slab.h>
 
···
 	 * so that we don't have to every time we make them.
 	 */
 	if ((!driver->message_send) || (!driver->message_cancel)) {
-		pr_err("Must implement all gb_hd_driver callbacks!\n");
+		dev_err(parent, "mandatory hd-callbacks missing\n");
 		return ERR_PTR(-EINVAL);
 	}
 

drivers/staging/greybus/operation.c

···
 	size_t message_size = payload_size + sizeof(*header);
 
 	if (message_size > hd->buffer_size_max) {
-		pr_warn("requested message size too big (%zu > %zu)\n",
+		dev_warn(&hd->dev, "requested message size too big (%zu > %zu)\n",
 				message_size, hd->buffer_size_max);
 		return NULL;
 	}