Commit 5620a0d1 ("firmware: delete in-kernel firmware") deleted
in-kernel firmware support, including the firmware install command.

So, the firmware package does not make sense any more.  Remove it.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NRiku Voipio <riku.voipio@linaro.org>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>