[X86] Remove AddedComplexity from register form of NOT. NFCI

I believe isProfitableToFold will stop the load folding that this was intended to overcome.

Given an (xor load, -1), isProfitableToFold will see that the immediate can be folded with the xor using a one byte immediate since it can be sign extended. It doesn't know about NOT, but the one byte immediate check is enough to stop the fold.

llvm-svn: 336712