buildroot

arch/arm: simplify hiding non 64-bit cores

Now that the cores are all oredered correctly, we can just enclose all
the non 64-bit cores inside a big if-block, rather than have each of
them have the dependency.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>