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>
Reviewed-on: https://review.coreboot.org/26726
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

util/sconfig/sconfig.tab.c_shipped

@@ -487,8 +487,8 @@ static const yytype_uint8 yytranslate[] =
 static const yytype_uint8 yyrline[] =
 {
        0,    36,    36,    36,    38,    38,    38,    38,    40,    40,
-      40,    40,    40,    40,    42,    42,    52,    52,    64,    67,
-      70,    73,    76
+      40,    40,    40,    40,    42,    42,    51,    51,    63,    66,
+      69,    72,    75
 };
 #endif
 
@@ -1311,7 +1311,6 @@ yyreduce:
 
     {
 	cur_chip = chip_dequeue_tail();
-	add_header((yyvsp[-2].chip));
 }
 
     break;