linux-phytec-ti

ARM: shmobile: R-Car: Improve documentation

Add more SYSC register documentation.
Use definitions instead of hardcoded numbers.
Comment important operations.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>