buildroot

package/miraclecast: drop legacy systemd-kdbus select

This options was recently removed and made it to legacy (in 815f7137739)
but miraclecast still selects it.

miraclecast builds fine without it, it seems, so just drop the select
altogether.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Cc: Ryan Barnett <rjbarnet@rockwellcollins.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>