ncsid: Fix if_packet warnings

The new Docker CI now hits the following error.
```
/usr/include/linux/if_packet.h:24:17: error: flexible array member 'sockaddr_ll::<unnamed union>::<unnamed struct>::sll_addr_flex' not at end of 'class ncsi::SockIO'
   24 |                 __DECLARE_FLEX_ARRAY(unsigned char, sll_addr_flex);
      |                 ^~~~~~~~~~~~~~~~~~~~
../subprojects/ncsid/src/ncsi_sockio.h:55:15: note: next member 'const int ncsi::SockIO::kpoll_timeout_' declared here
   55 |     const int kpoll_timeout_ = 10;
      |               ^~~~~~~~~~~~~~
../subprojects/ncsid/src/ncsi_sockio.h:29:7: note: in the definition of 'class ncsi::SockIO'
   29 | class SockIO : public net::SockIO
```

Removed the sockaddr_ll variable.

Change-Id: I67e700f6cd728bfbc822c1b8661915f8306711a1
Signed-off-by: Willy Tu <wltu@google.com>
diff --git a/subprojects/ncsid/src/net_iface.h b/subprojects/ncsid/src/net_iface.h
index 23bcb91..a60b6e3 100644
--- a/subprojects/ncsid/src/net_iface.h
+++ b/subprojects/ncsid/src/net_iface.h
@@ -55,7 +55,7 @@
      *     syscall, except that it fills in sll_ifindex field
      *     of struct sockaddr_ll with the index of this interface.
      */
-    virtual int bind_sock(int sockfd, struct sockaddr_ll* saddr) const = 0;
+    virtual int bind_sock(int sockfd) const = 0;
 
   protected:
     std::string name_;
@@ -89,7 +89,7 @@
      *     syscall, except that it fills in sll_ifindex field
      *     of struct sockaddr_ll with the index of this interface.
      */
-    int bind_sock(int sockfd, struct sockaddr_ll* saddr) const override;
+    int bind_sock(int sockfd) const override;
 
   private:
     /** @brief Similar to ioctl syscall, but the socket is created inside