imx: imx9: Set correct critical temperature

Commit 3233349f ("imx: imx9: fixup thermal trips from fuses")
wrongly set critical temperature to (maxc - 5) instead of maxc.

Fixes: 3233349f ("imx: imx9: fixup thermal trips from fuses")
Signed-off-by: Primoz Fiser <primoz.fiser@norik.com>