clk: renesas: rcar-gen2: Remove obsolete rcar_gen2_clocks_init()

The R-Car Gen2 board code no longer calls rcar_gen2_clocks_init().

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Dirk Behme <dirk.behme@de.bosch.com>