drivers: thermal: Kconfig: fix spelling mistake "acces" -> "access"

There is a spelling mistake in the Kconfig text, fix it.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20200810082739.48007-1-colin.king@canonical.com