util/sconfig: Re-factor emitting of headers to static.c

This change removes call to add_header from parsing functions and
moves it to a local function within main.c. It also adds a new
function emit_headers that is responsible for creating the linked list
for chip headers and emitting those to static.c

BUG=b:80081934
TEST=Verified that static.c for all files compiled using abuild is the
same with and without this change.

Change-Id: I24d526e81323115d3cc927242a4b9e49414afbe0
Signed-off-by: Furquan Shaikh <furquan@google.com>
---
M util/sconfig/main.c
M util/sconfig/sconfig.h
M util/sconfig/sconfig.tab.c_shipped
M util/sconfig/sconfig.y
4 files changed, 61 insertions(+), 56 deletions(-)