This patch fixes the following issue with string conversion of a MMCallStateReason enum:
mmcli-call.c:160:88: error: implicit conversion from enumeration type 'MMCallStateReason' to different enumeration type 'MMCallState' [-Werror,-Wenum-conversion]
mmcli_output_string (MMC_F_CALL_PROPERTIES_STATE_REASON, mm_call_state_get_string (mm_call_get_state_reason (call)));
~~~~~~~~~~~~~~~~~~~~~~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~