Add dev_delhandle() syscall to delete a device handle from process resources

kernel/syscall/syscall.c

@@ -64,6 +64,7 @@ SyscallFn SYSCALL_TABLE[SYSCALLS_MAX] = {
   [SYS_DEV_LISTSIZE]  = &sys_dev_listsize,
   [SYS_DEV_STAT]      = &sys_dev_stat,
   [SYS_DEV_CMD]       = &sys_dev_cmd,
+  [SYS_DEV_DELHANDLE] = &sys_dev_delhandle,
 
   [SYS_TIME]    = &sys_time,
 };