clk: renesas: r7s9210: Add SPIBSC clock

Add SPIBSC clock for RZ/A2.

Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
Link: https://lore.kernel.org/r/20191206134202.18784-4-chris.brandt@renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>