arm64: dts: renesas: sparrow-hawk-fan-pwm: Rework hwmon comment

arm64: dts: renesas: sparrow-hawk-fan-pwm: Rework hwmon comment

Reword fan DT overlay hwmon comment to accurately locate the fan control
sysfs hwmon node on Retronix R-Car V4H Sparrow Hawk.
No functional change.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20250907225338.426253-1-marek.vasut+renesas@mailbox.org
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>