mb/google/zork: Reorganize chromeos.fmd to increase WP_RO to 8MiB

mb/google/zork: Reorganize chromeos.fmd to increase WP_RO to 8MiB

This change reorganizes flash map layout for zork to allow WP_RO to
grow to 8MiB. This is to allow more space for the firmware UI screens
in RO. Following changes are made in the layout:

1. MRC_CACHE_HOLE is dropped since only one slot of 64K is used for
MRC cache. Next section can start on 64K boundary immediately after
MRC cache.
2. RW_SECTION_A and RW_SECTION_B are dropped down in size to 3MiB
each. Each region is currently at ~2MiB of usage.
3. RW_ELOG is restrictred to 4KiB as that is the maximum elog size
supported by coreboot.
4. SMMSTORE is restricted to 4K.
5. RW_LEGACY region is dropped down to ~1.9MiB.

BUG=b:161949925
TEST=Verified that write-protection for RO still works fine, device
boots in recovery and non-recovery mode. Also, verified that the dump
of fmap looks correct:
dump_fmap -h firmware/image-trembyle.serial.bin
name                     start       end         size
WP_RO                      00800000    01000000    00800000
  RO_SECTION                 00804000    01000000    007fc000
    COREBOOT                   00875000    01000000    0078b000
    GBB                        00805000    00875000    00070000
    RO_FRID                    00804800    00804840    00000040
    FMAP                       00804000    00804800    00000800
  RO_VPD                     00800000    00804000    00004000
RW_LEGACY                  0061d000    00800000    001e3000
SMMSTORE                   0061c000    0061d000    00001000
RW_NVRAM                   00617000    0061c000    00005000
RW_VPD                     00615000    00617000    00002000
RW_SHARED                  00611000    00615000    00004000
  VBLOCK_DEV                 00613000    00615000    00002000
  SHARED_DATA                00611000    00613000    00002000
RW_ELOG                    00610000    00611000    00001000
RW_SECTION_B               00310000    00610000    00300000
  RW_FWID_B                  0060ff00    00610000    00000100
  FW_MAIN_B                  00312000    0060ff00    002fdf00
  VBLOCK_B                   00310000    00312000    00002000
RW_SECTION_A               00010000    00310000    00300000
  RW_FWID_A                  0030ff00    00310000    00000100
  FW_MAIN_A                  00012000    0030ff00    002fdf00
  VBLOCK_A                   00010000    00012000    00002000
RW_MRC_CACHE               00000000    00010000    00010000
SI_BIOS                    00000000    01000000    01000000

Signed-off-by: Furquan Shaikh <furquan@google.com>
Change-Id: I882f3d813c08ba5fb0ad071da4f79e723296f4b0
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44362
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Joel Kitching <kitching@google.com>