Fix a const pointer usage warning in the Digigram miXart soundcard driver

Fix a const pointer usage warning in the Digigram miXart soundcard driver.  A
const pointer is being passed to copy_from_user() to load the firmware into.
This is okay in this case because the function has allocated the firmware
struct itself, but the const qualifier is part of the firmware struct - so the
patch casts the const away.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

sound/pci/mixart/mixart_hwdep.c

@@ -613,7 +613,7 @@ static int mixart_hwdep_dsp_load(struct snd_hwdep *hw,
 			   (int)dsp->length);
 		return -ENOMEM;
 	}
-	if (copy_from_user(fw.data, dsp->image, dsp->length)) {
+	if (copy_from_user((void *) fw.data, dsp->image, dsp->length)) {
 		vfree(fw.data);
 		return -EFAULT;
 	}