We recently changed these two pointers from void pointers to struct
pointers and it breaks the pointer math so now the "txphdr" points
beyond the end of the buffer.

Fixes: 56a967c4 ("net: qualcomm: rmnet: Remove some unneeded casts")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>