fmlib: only show comment if we're on a suitable arch

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/fmlib/Config.in

@@ -1,4 +1,5 @@
 comment "fmlib needs a Linux kernel to be built"
+	depends on BR2_powerpc_e500mc
 	depends on !BR2_LINUX_KERNEL
 
 config BR2_PACKAGE_FMLIB