mfd: tqmx86: Remove incorrect TQMx90UC board ID

No TQMx90UC exists at the moment, and it is undecided whether ID 10 will
be used eventually (and if it is, how that SoM will be named).

Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Lee Jones <lee.jones@linaro.org>