clk: renesas: r8a7796: Add SDIF clocks

This patch adds SDIF clocks for R8A7796 SoC.

Based on work by Ai Kyuse and Yoshihiro Shimoda for the r8a7795 SoC.

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