RLC: _req() accepts max TB size, _ind() not

Previously, the various rlc_*_ind() functions had a parameter to enable
the MAC to specify the max TB size that a subsequent call to the
corresponding rlc_*_req() (!) function would return. This patch removes
this parameter from the rlc_*_ind() functions and makes the parameter
working that is already in the rlc_*_req() functions.