drivers/sensor: lis2dh: move h/w reg debug print right after it is read

Move LOG_DBG print just after the printed h/w register is read, to avoid
coverity complaining about uninitialized variable.

  Fix:
     Coverity-CID: 316407 (issue #58591)

Signed-off-by: Armando Visconti <armando.visconti@st.com>