staging:iio:ade7854: Fix the wrong number of bits to read

Fixes: correctly handle the data size in the read operation for I2C

The function ade7854_i2c_read_reg_32() have to invoke the
i2c_master_recv() for read 32 bits values, however, the counter is set
to 3 which means 24 bits. This patch fixes the wrong size of 24 bits, to
32 bits.

Signed-off-by: John Syne <john3909@gmail.com>
Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Fixes: 8d97a587 ("staging: iio: meter: new driver for ADE7754 devices")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>