visium: drop .bss and .skip overrides

visium: drop .bss and .skip overrides

The comment in s_bss() looks bogus (perhaps simply stale, or wrongly
copied from another target). It also doesn't look to be a good idea to
override the custom handler that ELF has (afaict doing so broke
.previous as well as sub-section specification).

The override for .skip is simply pointless, for read.c having exactly
the same.

While there also drop two adjacent redundant (with read.h) declarations
(which would be outright dangerous if read.h wasn't included anyway).