iio: accel: mma8452: handle I2C read error(s) in mma8452_read()

iio: accel: mma8452: handle I2C read error(s) in mma8452_read()

Currently, If i2c_smbus_read_i2c_block_data() fails but
mma8452_set_runtime_pm_state() succeeds, mma8452_read() returns 0.

As a result, the caller mma8452_read_raw() assumes the read was
successful and proceeds to use a buffer containing uninitialized
stack memory.

Add proper checking of the I2C read return value and propagate errors
to the caller.

Fixes: 96c0cb2bbfe0 ("iio: mma8452: add support for runtime power management")
Signed-off-by: Sanjay Chitroda <sanjayembeddedse@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>