Both targets miss a subtarget causing an image naming style which is
different from other all othe targets, even tho it already uses
`x/generic/` as subfolder as if the subtarget would exist.
This commit adds the Generic subtarget resulting in consistent naming.
Fixes: c9e45c2 ("uboot-fritz4040: update PKG_MIRROR_HASH")
Fixes: bb43571 ("uboot-fritz4040: update to latest HEAD")
Signed-off-by: Paul Spooren <mail@aparcar.org>
(cherry picked from commit 853e4dd306)
