payloads/external/iPXE: Add more Kconfig options

Add two new options:
* Disable the prompt "Press Ctrl+B for the iPXE command line..."
Add a boolean that disables the initial 2 second timeout.

* Include a script that is executed instead of showing a shell.
Allows to add a script that will be included into the iPXE ROM.

Tested on Lenovo T500 and PC Engines apu2.

Change-Id: Ie1083d8571d9d1f1c7c71659fb6ff0de2eecad0e
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Signed-off-by: Michał Żygowski <michal.zygowski@3mdeb.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/20782
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

payloads/external/iPXE/Kconfig

@@ -87,5 +87,31 @@ config PXE_SERIAL_CONSOLE
 
 	  Unselect to let only SeaBIOS handle printing output.
 
+config PXE_NO_PROMT
+	bool "Do not show prompt to boot from PXE"
+	default n
+	depends on BUILD_IPXE
+	help
+	  Don't wait for the user to press Ctrl-B.
+	  The PXE still can be run as it shows up in SeaBIOS's payload list.
+
+config PXE_ADD_SCRIPT
+	bool "Embed an iPXE script for automated provisioning"
+	depends on BUILD_IPXE
+	default n
+	help
+	  Enable to embed a script that is run instead of an iPXE shell.
+
+config PXE_SCRIPT
+	string "Embedded iPXE script path and filename"
+	depends on PXE_ADD_SCRIPT
+	default ""
+	help
+	  Path to a script that is embedded into the iPXE binary.
+	  Example: startup.ipxe
+
+	  Uses the ipxe script instead showing the prompt:
+	  "Press Ctrl-B to start iPXE..."
+
 endmenu
 endif