[callstate] Tune diagnostic logging and other minor fixes
[callstate] Tune diagnostic logging and other minor fixes

Use warning level for reporting invalid parameters supplied by client
and error level for reporting internal failures.

Use appropriate call state and type constants instead of the generic
MCE_INVALID_TRANSLATION.

Use !xxx() instead of xxx() == FALSE in conditionals.

No functional changes.

kimmoli/mce,kimmoli/mce,mlehtima/mce,spiiroin/mce,mikkoharju/mce,android-808/mce,spiiroin/mce,android-808/mce,mlehtima/mce,spiiroin/mce,mikkoharju/mce,kimmoli/mce,spiiroin/mce,mlehtima/mce,mikkoharju/mce,android-808/mce,mlehtima/mce,maikelwever/mce,maikelwever/mce,android-808/mce,maikelwever/mce,maikelwever/mce,mikkoharju/mce,kimmoli/mce