iio: pressure: mprls0025pa: change measurement sequence

iio: pressure: mprls0025pa: change measurement sequence

Implement a measurement sequence that does not involve a one byte read of
the status byte before reading the conversion.

The sensor's conversions should be read either once the EoC interrupt
has triggered or 5ms after the 0xaa command. See Options 1 and 2
respectively in Tables 16 (page 15) and 18 (page 18) of the datasheet.
Note that Honeywell's example code also covered in the datasheet follows
Option 2 for both i2c and SPI.

The datasheet does not specify any of the retry parameters that are
currently implemented in the driver. A simple 5+ms sleep as specified in
Option 2 is enough for a valid measurement sequence.

The change also gets rid of the code duplication tied to the verification
of the status byte.

This change only affects users that do not define the EoC interrupt in
the device tree.

Datasheet: https://prod-edam.honeywell.com/content/dam/honeywell-edam/sps/siot/en-us/products/sensors/pressure-sensors/board-mount-pressure-sensors/micropressure-mpr-series/documents/sps-siot-mpr-series-datasheet-32332628-ciid-172626.pdf?download=false
Signed-off-by: Petre Rodan <petre.rodan@subdimension.ro>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>