long vs. unsigned long - low-hanging fruits in drivers

deal with signedness of the stuff passed to set_bit() et.al.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/dsp56k.c b/drivers/char/dsp56k.c
index acbfe1c..a69c652 100644
--- a/drivers/char/dsp56k.c
+++ b/drivers/char/dsp56k.c
@@ -136,7 +136,7 @@
 
 
 static struct dsp56k_device {
-	long in_use;
+	unsigned long in_use;
 	long maxio, timeout;
 	int tx_wsize, rx_wsize;
 } dsp56k;