[ALSA] Remove sound/driver.h

This header file exists only for some hacks to adapt alsa-driver
tree.  It's useless for building in the kernel.  Let's move a few
lines in it to sound/core.h and remove it.
With this patch, sound/driver.h isn't removed but has just a single
compile warning to include it.  This should be really killed in
future.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

sound/usb/usbmidi.c

@@ -35,7 +35,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sound/driver.h>
 #include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/bitops.h>