xfrm_algo: drop an unnecessary inclusion

For several releases, this has not been needed anymore, as no helper
functions declared in net/ah.h get implemented by xfrm_algo.c anymore.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/xfrm/xfrm_algo.c

@@ -15,9 +15,6 @@
 #include <linux/crypto.h>
 #include <linux/scatterlist.h>
 #include <net/xfrm.h>
-#if defined(CONFIG_INET_AH) || defined(CONFIG_INET_AH_MODULE) || defined(CONFIG_INET6_AH) || defined(CONFIG_INET6_AH_MODULE)
-#include <net/ah.h>
-#endif
 #if defined(CONFIG_INET_ESP) || defined(CONFIG_INET_ESP_MODULE) || defined(CONFIG_INET6_ESP) || defined(CONFIG_INET6_ESP_MODULE)
 #include <net/esp.h>
 #endif