iio: adc: ade9000: fix wrong register in CALIBBIAS case for active power

The switch statement in ade9000_write_raw() attempts to match
chan->address against ADE9000_REG_AWATTOS (0x00F) to dispatch
the calibration offset write for active power channels. However,
chan->address is set via ADE9000_ADDR_ADJUST(ADE9000_REG_AWATT,
num), so after masking the phase bits, tmp holds
ADE9000_REG_AWATT (0x210), which never matches 0x00F.

As a result, writing IIO_CHAN_INFO_CALIBBIAS for IIO_POWER always
falls through to the default case and returns -EINVAL, making
active power offset calibration silently broken.

Fix this by matching against ADE9000_REG_AWATT instead, which is
the actual base address stored in chan->address for watt channels.

Reference:ADE9000 datasheet (Rev. B), AWATTOS is the offset correction
register at 0x00F (p. 44), while AWATT is the total active power
register at 0x210 (p. 48).

Fixes: 81de7b4619fc ("iio: adc: add ade9000 support")
Signed-off-by: Giorgi Tchankvetadze <giorgitchankvetadze1997@gmail.com>
Reviewed-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>