HID: hidraw: Replace Confusing += Operator with =

Setting of the return value of hidraw_read() uses the += operator when
= is more appropriate.  There is no case where ret can be anything
other than zero when the assignment is made, making = equivalent to
+= and much more clear.

Signed-off-by: Alan Ott <alan@signal11.us>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index 468e87b..66fbcba 100644
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -91,7 +91,7 @@
 			ret = -EFAULT;
 			goto out;
 		}
-		ret += len;
+		ret = len;
 
 		kfree(list->buffer[list->tail].value);
 		list->tail = (list->tail + 1) & (HIDRAW_BUFFER_SIZE - 1);