ALSA: korg1212: Add __force annotation to cast in user-copy callbacks

The user-copy callbacks in korg1212 driver contain the explicit cast
from a user pointer to a kernel pointer, but they missed __force
prefix.  It's mandatory for converting between them.

Spotted by sparse, a warning like:
  sound/pci/korg1212/korg1212.c:1329:33: warning: cast removes address space of expression
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/korg1212/korg1212.c

@@ -1326,7 +1326,7 @@ static int snd_korg1212_copy_to(struct snd_pcm_substream *substream,
 		}
 #endif
 		if (in_kernel)
-			memcpy((void *)dst, src, size);
+			memcpy((__force void *)dst, src, size);
 		else if (copy_to_user(dst, src, size))
 			return -EFAULT;
 		src++;
@@ -1365,7 +1365,7 @@ static int snd_korg1212_copy_from(struct snd_pcm_substream *substream,
 		}
 #endif
 		if (in_kernel)
-			memcpy((void *)dst, src, size);
+			memcpy(dst, (__force void *)src, size);
 		else if (copy_from_user(dst, src, size))
 			return -EFAULT;
 		dst++;