lib.sh: support any command on find_exec()

right now, we assume "find", but it adds any number of
arguments next to that.

change it instead to support any command, where the
assumption is that it would generate a list of files
and directories.

Signed-off-by: Leah Rowe <leah@libreboot.org>

include/rom.sh

@@ -192,7 +192,7 @@ mkseagrub()
 	[ "$payload_grubsea" = "y" ] && pname="grub"
 	[ "$payload_grubsea" = "y" ] || \
 	    cbfs "$tmprom" "$grubdata/bootorder" bootorder raw
-	fe_ "cprom" "$grubdata/keymap" -type f -name "*.gkb"
+	fe_ cprom find "$grubdata/keymap" -type f -name "*.gkb"
 }
 
 add_uboot()