clk: renesas: r8a7795: Fix HDMI parent clock

Correct HDMI parent clock so that the rate of the
HDMI clock is 1/4 rather than 1/2 of the rate of PLL1
as per the v0.52 (Jun, 15) manual.

Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>