b43legacy: Fix sparse warnings

Sparse yields the following warnings for b43legacy:

  CHECK   drivers/net/wireless/b43legacy/phy.c
drivers/net/wireless/b43legacy/phy.c:1304:31: warning: potentially expensive pointer subtraction
drivers/net/wireless/b43legacy/phy.c:1304:31: warning: potentially expensive pointer subtraction
drivers/net/wireless/b43legacy/phy.c:1304:31: warning: potentially expensive pointer subtraction
  CHECK   drivers/net/wireless/b43legacy/debugfs.c
drivers/net/wireless/b43legacy/debugfs.c:243:9: warning: memset with byte count of 131072

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/b43legacy/debugfs.c b/drivers/net/wireless/b43legacy/debugfs.c
index 03ce082..1f85ac5 100644
--- a/drivers/net/wireless/b43legacy/debugfs.c
+++ b/drivers/net/wireless/b43legacy/debugfs.c
@@ -211,7 +211,7 @@
 	struct b43legacy_dfs_file *dfile;
 	ssize_t uninitialized_var(ret);
 	char *buf;
-	const size_t bufsize = 1024 * 128;
+	const size_t bufsize = 1024 * 16; /* 16 KiB buffer */
 	const size_t buforder = get_order(bufsize);
 	int err = 0;