mfd: intel_quark_i2c_gpio: Adjust IOT2000 matching

mfd: intel_quark_i2c_gpio: Adjust IOT2000 matching

Since there are more IOT2040 variants with identical hardware but
different asset tags, the asset tag matching should be adjusted to
support them.

For the board name "SIMATIC IOT2000", currently there are 2 types of
hardware, IOT2020 and IOT2040. Both are identical regarding the
intel_quark_i2c_gpio. In the future there will be no other devices with
the "SIMATIC IOT2000" DMI board name but different hardware. So remove
the asset tag matching from this driver.

Signed-off-by: Su Bao Cheng <baocheng.su@siemens.com>
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>