d80211: bitfield usage should go

I'm doing an in-depth review of d80211 right now.

One issue that leaps out:  use of bitfields.

1) single-bit signed bitfields are undefined

	int wep_include_iv:1;

2) bitfields in general generate HORRIBLE code.  Just don't use them. 
Compilers often fail to use even the most obvious simplifications.

Use flags and bitwise operators instead, like most other Linux code.