vboot: remove VBOOT_SAVE_RECOVERY_REASON_ON_REBOOT option

With CL:1940398, this option is no longer needed.  Recovery
requests are not cleared until kernel verification stage is
reached.  If the FSP triggers any reboots, recovery requests
will be preserved.  In particular:

- Manual requests will be preserved via recovery switch state,
  whose behaviour is modified in CB:38779.
- Other recovery requests will remain in nvdata across reboot.

These functions now only work after verstage has run:
  int vboot_check_recovery_request(void)
  int vboot_recovery_mode_enabled(void)
  int vboot_developer_mode_enabled(void)

BUG=b:124141368, b:35576380
TEST=make clean && make test-abuild
BRANCH=none

Change-Id: I52d17a3c6730be5c04c3c0ae020368d11db6ca3c
Signed-off-by: Joel Kitching <kitching@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38780
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/security/vboot/vbnv.c

@@ -101,26 +101,6 @@ void save_vbnv(const uint8_t *vbnv_copy)
 	vbnv_initialized = 0;
 }
 
-/* Save a recovery reason into VBNV. */
-void set_recovery_mode_into_vbnv(int recovery_reason)
-{
-	uint8_t vbnv_copy[VBOOT_VBNV_BLOCK_SIZE];
-
-	read_vbnv(vbnv_copy);
-
-	vbnv_copy[RECOVERY_OFFSET] = recovery_reason;
-	vbnv_copy[CRC_OFFSET] = crc8_vbnv(vbnv_copy, CRC_OFFSET);
-
-	save_vbnv(vbnv_copy);
-}
-
-/* Read the recovery reason from VBNV. */
-int get_recovery_mode_from_vbnv(void)
-{
-	vbnv_setup();
-	return vbnv[RECOVERY_OFFSET];
-}
-
 /* Read the USB Device Controller(UDC) enable flag from VBNV. */
 int vbnv_udc_enable_flag(void)
 {