Add clocks for SPIBSC blocks.

Also modify the flash node for the GR-PEACH board at the same time
because now that the SPIBSC clock is identified, if it is not used
by any driver, it will be turned off at the end of kernel boot.
That would not work out so well for an XIP system such as GR-PEACH.
Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
Link: https://lore.kernel.org/r/20200210123153.8257-1-chris.brandt@renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>