Revert "arm64: dts: r8a7795: Add CPUIdle support for all CPU core"

This reverts commit c93bf81f

.

Support cpu ilde feature, there are still other related patches
need to be applied, but as a basic BSP, it doesn't recommend to
merge lots of patches to standard/base branch.
In addtional, only get one patch of cpu ilde feature cause system
unstable, so revert it.

Signed-off-by: Meng Li <Meng.Li@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>