ltq-tapi: Fix compile with kernel 5.15

Do not use find_vpid(), but get_task_pid() to get the pid from
pThrCntrl->tid. This is now a ponter to struct task_struct instead of
an integer.

This fixes the build of ltq-tapi with lantiq/xway.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

package/kernel/lantiq/ltq-tapi/patches/510-linux-515.patch

@@ -0,0 +1,14 @@
+--- a/src/drv_tapi_linux.c
++++ b/src/drv_tapi_linux.c
+@@ -3779,8 +3779,10 @@ IFX_void_t TAPI_OS_ThreadKill(IFXOS_Thre
+          mb();
+ #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,28)
+          kill_proc(pThrCntrl->tid, SIGKILL, 1);
+-#else
++#elif LINUX_VERSION_CODE < KERNEL_VERSION(3,8,0)
+          kill_pid(find_vpid(pThrCntrl->tid), SIGKILL, 1);
++#else
++         kill_pid(get_task_pid(pThrCntrl->tid, PIDTYPE_PID), SIGKILL, 1);
+ #endif
+          /* release the big kernel lock */
+ #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,33)