[PPP]: Sparse warning fixes.

Fix a bunch of warnings in PPP and related drivers. Mostly because
sparse doesn't like it when the the function is only marked private in
the forward declaration.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ppp_deflate.c b/drivers/net/ppp_deflate.c
index eb98b66..034c1c6 100644
--- a/drivers/net/ppp_deflate.c
+++ b/drivers/net/ppp_deflate.c
@@ -206,7 +206,7 @@
  *	Returns the length of the compressed packet, or 0 if the
  *	packet is incompressible.
  */
-int z_compress(void *arg, unsigned char *rptr, unsigned char *obuf,
+static int z_compress(void *arg, unsigned char *rptr, unsigned char *obuf,
 	       int isize, int osize)
 {
 	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
@@ -435,7 +435,7 @@
  * bug, so we return DECOMP_FATALERROR for them in order to turn off
  * compression, even though they are detected by inspecting the input.
  */
-int z_decompress(void *arg, unsigned char *ibuf, int isize,
+static int z_decompress(void *arg, unsigned char *ibuf, int isize,
 		 unsigned char *obuf, int osize)
 {
 	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;