Add device nodes for the Timer Units (TMU) on the RZ/G1H (R8A7742),
RZ/G1M (R8A7743), RZ/G1N (R8A7744), RZ/G1E (R8A7745), and RZ/G1C
(R8A77470) SoCs.

Note that TMU channel 0 on RZ/G1C is not added, as its module clock is
not documented.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/b09f55e0089a9824d43e89fd6bac3cbd48f40d8b.1710864964.git.geert+renesas@glider.be