cbfs: Rename TYPE_FIT to TYPE_FIT_PAYLOAD

There are too many "FIT" in firmware land. In order to reduce possible
confusion of CBFS_TYPE_FIT with the Intel Firmware Interface Table, this
patch renames it to CBFS_TYPE_FIT_PAYLOAD (including the cbfstool
argument, so calling scripts will now need to replace `-t fit` with `-t
fit_payload`).

Signed-off-by: Julius Werner <jwerner@chromium.org>
Change-Id: I826cefce54ade06c6612c8a7bb53e02092e7b11a
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64735
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>

src/lib/prog_loaders.c

@@ -160,7 +160,7 @@ void payload_load(void)
 	case CBFS_TYPE_SELF: /* Simple ELF */
 		selfload_mapped(payload, mapping, BM_MEM_RAM);
 		break;
-	case CBFS_TYPE_FIT: /* Flattened image tree */
+	case CBFS_TYPE_FIT_PAYLOAD: /* Flattened image tree */
 		if (CONFIG(PAYLOAD_FIT_SUPPORT)) {
 			fit_payload(payload, mapping);
 			break;