ARM: 9212/1: domain: Modify Kconfig help text

ARM: 9212/1: domain: Modify Kconfig help text

[ Upstream commit 2bf6204240fddb22cc4940b9e3f40c538390212e ]

After the removal of set_fs() the reference to set_fs() is stale.
Alter the helptext to reflect what the config option really does.

Fixes: 8ac6f5d7f84b ("ARM: 9113/1: uaccess: remove set_fs() implementation")
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>