thermal: imx8mm: Fix build warning of incorrect argument type

Fix below sparse warning:

drivers/thermal/imx8mm_thermal.c:82:36: sparse: sparse: incorrect type in argument 2 (different address spaces), expected unsigned long const volatile *addr
drivers/thermal/imx8mm_thermal.c:82:36: sparse: expected unsigned long const volatile *addr

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1584973156-25734-1-git-send-email-Anson.Huang@nxp.com