arm64: dts: renesas: salvator-xs: Improve SATA switch settings comments

The comments describing the non-default switch settings to use SATA are
confusing: 'Off' refers to the switch position, not to the MD12 logic
value, while the parentheses suggest otherwise.  Rephrase to fix this.

Fixes: bec000784d5bb571 ("arm64: dts: renesas: salvator-xs: enable SATA")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>