clk: renesas: r8a7778: Remove obsolete r8a7778_clocks_init()

The R-Car M1A board code no longer calls r8a7778_clocks_init().

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