clk: vc5: Add properties for configuring SD/OE behavior

The SD/OE pin may be configured to enable output when high or low, and
to shutdown the device when high. This behavior is controller by the SH
and SP bits of the Primary Source and Shutdown Register (and to a lesser
extent the OS and OE bits). By default, both bits are 0 (unless set by
OTP memory), but they may need to be configured differently, depending
on the external circuitry controlling the SD/OE pin.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Link: https://lore.kernel.org/r/20210809223813.3766204-3-sean.anderson@seco.com
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>