clk: renesas: r7s9210: Add SPI clocks

Add RSPI clocks for RZ/A2.

Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>