Regroup all asm calls into functions and declare all of them inline

[L3nn0x]

[Yamakaky]

inline is useless, the compiler with -Os already auto-inline.
They are still some __asm in drivers/ because hwi is complicated: it can use variable registers on input and output and modify memory. I'm sticking to inline asm for now, I will refactor it when I will know better what to do.