qemu: Correct CMD_QFW dependencies in Kconfig

Rather than selecting CMD_QFW, we should make the option itself by
enabled by default on these platforms.  Then in the board-specific
Kconfig we should select the appropriate back-end as needed if the
command is enabled.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index df6d71c..7ff77a7 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -2257,6 +2257,8 @@
 config CMD_QFW
 	bool "qfw"
 	select QFW
+	default y if TARGET_QEMU_ARM_32BIT || TARGET_QEMU_ARM_64BIT || \
+		TARGET_QEMU_X86 || TARGET_QEMU_X86_64
 	help
 	  This provides access to the QEMU firmware interface.  The main
 	  feature is to allow easy loading of files passed to qemu-system