iio: adc: aspeed: Remove the trim valid dts property.

The dts property "aspeed,trim-data-valid" is currently used to determine
whether to read trimming data from the OTP register. If this is set on
a device without valid trimming data in the OTP the ADC will not function
correctly. This patch drops the use of this property and instead uses the
default (unprogrammed) OTP value of 0 to detect when a fallback value of
0x8 should be used rather then the value read from the OTP.

Fixes: d0a4c17b ("iio: adc: aspeed: Get and set trimming data.")
Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com>
Link: https://lore.kernel.org/r/20221114025057.10843-1-billy_tsai@aspeedtech.com


Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>