buildroot

package/linux: drop useless intermediate DTS booleans

Just use whatever the user specified in the list. An empty list means no
DTS was specified.

No need to add legacy option, as the behaviour does not change.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Simon van der Veldt <simon.vanderveldt@gmail.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Cc: Peter Korsgaard <peter@korsgaard.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Tested-by: Joshua Henderson <joshua.henderson@microchip.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>