soc: actions: Update SPS help text for S700

Commit 3ad85b08 (soc: actions: sps: Add S700)
added S700 support to the SPS driver but forget to update Kconfig help.

Add missing S700 mention, in preparation for further SoCs.

Fixes: 3ad85b08 ("soc: actions: sps: Add S700")
Reported-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Andreas Färber <afaerber@suse.de>

drivers/soc/actions/Kconfig

@@ -10,7 +10,7 @@ config OWL_PM_DOMAINS
 	select PM_GENERIC_DOMAINS
 	help
 	  Say 'y' here to enable support for Smart Power System (SPS)
-	  power-gating on Actions Semiconductor S500 SoC.
+	  power-gating on Actions Semiconductor S500 and S700 SoCs.
 	  If unsure, say 'n'.
 
 endif