clk: renesas: Minor clean up of the R8A7794 clock driver

The initconst is not used in U-Boot, drop it. The r8a7794_crit_mod_clks
is also not used in U-Boot, so drop it too.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>