The R-Car CAN controllers can derive the CAN bus clock not only from
their peripheral clock input (clkp1) but also from the other internal
clock (clkp2) and the external clock fed on the CAN_CLK pin. Describe
those clocks in the R8A7792 device tree.
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>