Consider RecvonlyStream and None (sendrecv) hold types
as NonHold methods.
Fixes:
16: 52:44 CallLeg.cpp: In member function 'CallLeg::holdMethod CallLeg::updateHoldMethod(const AmSdp&)':
16: 52:44 CallLeg.cpp:1421:10: warning: enumeration value 'None' not handled in switch [-Wswitch]
16: 52:44 1421 | switch (hold_method)
16: 52:44 | ^
Change-Id: I2021dd7152ad258e03c28c56cb3b0c7a5e363266