arm: fix wording of "Crotex" in CONFIG_ARCH_EXYNOS3 help

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: trivial@kernel.org
Signed-off-by: Jiri Kosina <jkosina@suse.cz>