hodec2: clarify current and target rxlev per candidate

Store the rxlev of the current lchan and the target BTS in the
ho_candidate, to clarify the code.

No functional change, cosmetically prepare for
I2704899c85c35dfd4eba43468452483f40016ca2.

Change-Id: Ie6c165e17bb3c99eebc967a6bb02529db8bdfc98
1 file changed