cbfs: Remove broken remnants of PAYLOAD_INFO feature

PAYLOAD_INFO is a very old feature that can add a key/value information
section to a payload file. It seems to have only ever been generated by
coreinfo and never really read by anything.

Since CB:1721 in 2012, the feature has been inadvertently broken in
practice since the `.note.pinfo` sections that contain the information
get discarded from the payload before cbfstool gets to see them. Since
CB:28647 in 2018, support for the section in the SELF loader was
(inadvertently?) dropped, so if someone actually fed cbfstool a payload
ELF that did have a `.note.pinfo` section, modern coreboot would refuse
to boot the payload entirely (which is probably not a good state to
leave things in).

This patch removes the code to generate PAYLOAD_INFO entries entirely,
but leaves the support to parse and extract those sections from old
payloads in place in cbfstool.

Change-Id: I40d8e9b76a171ebcdaa2eae02d54a1ca5e592c85
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/81087
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

payloads/libpayload/include/libpayload.h

@@ -84,18 +84,6 @@ static inline u32 div_round_up(u32 n, u32 d) { return (n + d - 1) / d; }
 
 #define MAX_ARGC_COUNT 32
 
-/*
- * Payload information parameters - these are used to pass information
- * to the entity loading the payload.
- * Usage:   PAYLOAD_INFO(key, value)
- * Example: PAYLOAD_INFO(name, "CoreInfo!")
- */
-#define _pstruct(key) __pinfo_ ##key
-#define PAYLOAD_INFO(key, value)                                        \
-static const char _pstruct(key)[]                                        \
-  __attribute__((__used__))                                              \
-  __attribute__((section(".note.pinfo"),unused)) = #key "=" value
-
 /**
  * @defgroup nvram NVRAM and RTC functions
  * @{