boot: provide CONFIG_BOOTMETH_QFW Kconfig parameter

U-Boot is often used conjunction with QEMU to boot via EFI or syslinux.
Here the QFW boot method is not needed.

At least for qemu-riscv64_smode_defconfig the kernel parameter is used
to specify the U-Boot binary. Trying to run U-Boot as a kernel makes
no sense.

Provide Kconfig parameter CONFIG_BOOTMETH_QFW to decide if the QFW boot
method shall be provided.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

boot/Kconfig

@@ -585,6 +585,15 @@ config BOOTMETH_EFI_BOOTMGR
 	  the EFI binary to be launched is determined. To set the EFI variables
 	  use the eficonfig command.
 
+config BOOTMETH_QFW
+	bool "Boot method using QEMU parameters"
+	depends on QFW
+	default y
+	help
+	 Use QEMU parameters -kernel, -initrd, -append to determine the kernel,
+	 initial RAM disk, and kernel command line parameters to boot an
+	 operating system. U-Boot's control device-tree is passed to the kernel.
+
 config BOOTMETH_VBE
 	bool "Bootdev support for Verified Boot for Embedded"
 	depends on FIT

boot/Makefile

@@ -11,7 +11,6 @@ obj-$(CONFIG_CMD_BOOTZ) += bootm.o bootm_os.o
 obj-$(CONFIG_CMD_BOOTI) += bootm.o bootm_os.o
 
 obj-$(CONFIG_PXE_UTILS) += pxe_utils.o
-obj-$(CONFIG_QFW) += bootmeth_qfw.o
 
 endif
 
@@ -31,6 +30,7 @@ obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_EXTLINUX) += bootmeth_extlinux.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_EXTLINUX_PXE) += bootmeth_pxe.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_EFILOADER) += bootmeth_efi.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_CROS) += bootm.o bootm_os.o bootmeth_cros.o
+obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_QFW) += bootmeth_qfw.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_SANDBOX) += bootmeth_sandbox.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_SCRIPT) += bootmeth_script.o
 obj-$(CONFIG_$(SPL_TPL_)CEDIT) += cedit.o