[PPP]: remove redundant NULL pointer checks before kfree & vfree

kfree() and vfree() can both deal with NULL pointers. This patch removes 
redundant NULL pointer checks from the ppp code in drivers/net/
Signed-off-by: Jesper Juhl <juhl-lkml@dif.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ppp_deflate.c

@@ -87,7 +87,6 @@ static void z_comp_free(void *arg)
 
 	if (state) {
 		zlib_deflateEnd(&state->strm);
-		if (state->strm.workspace)
 		vfree(state->strm.workspace);
 		kfree(state);
 	}
@@ -308,7 +307,6 @@ static void z_decomp_free(void *arg)
 
 	if (state) {
 		zlib_inflateEnd(&state->strm);
-		if (state->strm.workspace)
 		kfree(state->strm.workspace);
 		kfree(state);
 	}

drivers/net/ppp_generic.c

@@ -2467,14 +2467,10 @@ static void ppp_destroy_interface(struct ppp *ppp)
 	skb_queue_purge(&ppp->mrq);
 #endif /* CONFIG_PPP_MULTILINK */
 #ifdef CONFIG_PPP_FILTER
-	if (ppp->pass_filter) {
 	kfree(ppp->pass_filter);
 	ppp->pass_filter = NULL;
-	}
-	if (ppp->active_filter) {
 	kfree(ppp->active_filter);
 	ppp->active_filter = NULL;
-	}
 #endif /* CONFIG_PPP_FILTER */
 
 	kfree(ppp);