arm64: dts: rockchip: Add cache information to the SoC dtsi for RK3399

arm64: dts: rockchip: Add cache information to the SoC dtsi for RK3399

Add missing cache information to the Rockchip RK3399 SoC dtsi.  The specified
values were derived by hand from the cache size specifications available from
the RK3399 datasheet;  for future reference, here's a brief summary:

  - Each Cortex-A72 core has 48 KB of L1 instruction cache and
    32 KB of L1 data cache available, four-way set associative
  - Each Cortex-A53 core core has 32 KB of instruction cache and
    32 KB of L1 data cache available, four-way set associative
  - The big (A72) cluster has 1 MB of unified L2 cache available
  - The little (A53) cluster has 512 KB of unified L2 cache available

This patch allows /proc/cpuinfo and lscpu(1) to display proper RK3399 cache
information, and it eliminates the following error in the kernel log:

  cacheinfo: Unable to detect cache hierarchy for CPU 0

While there, add a couple of somewhat useful comments, which may help a bit
anyone going through the RK3399 SoC dtsi.

Co-developed-by: Kyle Copperfield <kmcopper@danwin1210.me>
Signed-off-by: Kyle Copperfield <kmcopper@danwin1210.me>
Signed-off-by: Dragan Simic <dsimic@manjaro.org>
Link: https://lore.kernel.org/r/be3cbcae5c40fa72a52845d30dcc66c847a98cfa.1702616304.git.dsimic@manjaro.org
Signed-off-by: Heiko Stuebner <heiko@sntech.de>