* Set correct xpd curve indices for high/low gain curves during
   rfbuffer setup on RF5112B with both calibration curves available.

 * Don't return zero min power when we have the same pcdac value
   twice because it breaks interpolation. Instead return the right
   x barrier as we do when we have equal power levels for 2 different
   pcdac values.
Signed-off-by: NNick Kossifidis <mickflemm@gmail.com>
Acked-by: NBob Copeland <me@bobcopeland.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>