By duplicating a little bit of code between 3945
and agn, we can move a lot of code into an agn
specific station management file and thus reduce
the amount of code in core that is dead to 3945.
before:
text data bss dec hex filename
212886 3872 96 216854 34f16 iwlcore.ko
620542 10448 304 631294 9a1fe iwlagn.ko
314013 3264 196 317473 4d821 iwl3945.ko
after:
text data bss dec hex filename
202857 3872 92 206821 327e5 iwlcore.ko
629102 10448 308 639858 9c372 iwlagn.ko
314240 3264 196 317700 4d904 iwl3945.ko