payloads: allow selecting a file for FLAT_BINARY

085c97363ed6477c64b61263a59d7e9642e05cda introduced a bug in that we
could not select a file to use, and, in fact, the payload was never
installed into the image in this case.

Add FLAT_BINARY to the predicate enabling a file selection dialog.

Change-Id: I8174b656b1e6ebb3663172f473e4070b30f19126
Signed-off-by: Ronald G Minnich <rminnich@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/81183
Reviewed-by: Maximilian Brune <maximilian.brune@9elements.com>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Philipp Hug <philipp@hug.cx>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/payloads/Kconfig b/payloads/Kconfig
index d18c1b0..ec1d40c 100644
--- a/payloads/Kconfig
+++ b/payloads/Kconfig
@@ -59,7 +59,7 @@
 
 config PAYLOAD_FILE
 	string "Payload path and filename"
-	depends on PAYLOAD_ELF || PAYLOAD_FIT
+	depends on PAYLOAD_ELF || PAYLOAD_FIT || PAYLOAD_FLAT_BINARY
 	default "payload.elf" if PAYLOAD_ELF
 	default "uImage" if PAYLOAD_FIT
 	help