util/amdfwtool: Maintain one copy of PSP Level2 entries

AMDFWtool maintains 2 copies of PSP Level2 entries - one in primary slot
A (Type 0x48) and another in backup slot B (Type 0x4A). On boards which
use VBOOT with 2 RW firmware slots, maintaining 2 copies of PSP Level2
entries in each FW slot is redundant and space-consuming. Introduce
option to maintain only one copy of PSP Level2 entries and point to it
from both slots A & B.

BUG=None
TEST=Build and boot to OS in Skyrim. Ensure that only one copy is added
to each FW slot. This achieved a space saving of 1.5 MB in each FW slot.
Before:
apu/amdfw                      0x415fc0   raw           3043328 none
After:
apu/amdfw                      0x415fc0   raw           1556480 none

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Change-Id: I06eef8e14b9c14db1d02b621c2f7207188d86326
Reviewed-on: https://review.coreboot.org/c/coreboot/+/63509
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

util/amdfwtool/amdfwtool.h

@@ -279,6 +279,7 @@ typedef struct _amd_cb_config {
 	bool second_gen;
 	bool have_mb_spl;
 	bool recovery_ab;
+	bool recovery_ab_single_copy;
 	bool need_ish;
 } amd_cb_config;