isdn: eicon: Use offsetof
isdn: eicon: Use offsetof

Use offsetof instead of explicit implementation.

* fixes bug with omitted & like:
  len = (byte)(((T30_INFO *) 0)->station_id + 20)

* avoids compiler warnings with wrong sizes (pointer-to-char cast):
  len = (byte)(&(((T30_INFO *) 0)->universal_6));

* cleans up the code

Signed-off-by: Jiri Slaby <aeaaaa09d9a5fac7c38743ea79aa4bb8ffb08290@gmail.com>
Cc: Karsten Keil <49f1bb9db9887b2592204b53c4cd2e640734837a@linux-pingi.de>
Acked-by: Armin Schindler <c16df42f50a572087367cc84d202696cf3ff1960@melware.de>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs