packages: drop DEVICE specific dependency for omnia

packages: drop DEVICE specific dependency for omnia

Both packages `ombnia-mcu-firmware` and `omnia-mcutool` would depend on
a specific device. The buildbots however build all devices and therefore
the package isn't build at all, due to unmet dependencies.

While this didn't cause issues with OPKG, APK fails actively due to the
missing packages. Drop the specific dependency, however wants to install
unrelated firmware on any device can do that anyway.

Signed-off-by: Paul Spooren <mail@aparcar.org>
(cherry picked from commit f35a29d63f445d784f1e266eaa6d3825a249cd6c)
Link: https://github.com/openwrt/openwrt/pull/17097
Signed-off-by: Petr Štetiar <ynezz@true.cz>