[logging] fix benign typecast issue in otDump (#5198)
[logging] fix benign typecast issue in otDump (#5198)

Fixes a benign typecast issue found when using the IAR compiler.
srickardti/openthread,lanyuwen/openthread,bukepo/openthread,abtink/openthread,jwhui/openthread,srickardti/openthread,chshu/openthread,jwhui/openthread,abtink/openthread,openthread/openthread,lanyuwen/openthread,bukepo/openthread,lanyuwen/openthread,lanyuwen/openthread,bukepo/openthread,srickardti/openthread,lanyuwen/openthread,openthread/openthread,chshu/openthread,openthread/openthread,lanyuwen/openthread,chshu/openthread,bukepo/openthread,srickardti/openthread,abtink/openthread,jwhui/openthread,jwhui/openthread,chshu/openthread,chshu/openthread,openthread/openthread,abtink/openthread,chshu/openthread