The R5 lockstep disabling should be common for all PG2 boards, move it
from variants dts to common-pg2.dtsi.

As now the Basic PG2 consumes this twice, move Basic disabling to the
PG1 variant.
Signed-off-by: Baocheng Su <baocheng.su@siemens.com>
[Jan: avoid duplication of disabling for Basic PG2]
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Link: https://lore.kernel.org/r/f692d0211915aefd4de7c9ecff5234683c9c7d59.1707463401.git.jan.kiszka@siemens.comSigned-off-by: Vignesh Raghavendra <vigneshr@ti.com>