sdp: log unhandled lines at LS_VERBOSE level
sdp: log unhandled lines at LS_VERBOSE level

for consistency with
  https://webrtc-review.googlesource.com/c/src/+/196526

Bug: None
Change-Id: Iddeb5e1639444e855e61d10d13c7a741916b658e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/196642
Commit-Queue: Philipp Hancke <563b103f57dc2044b12822c2a7559aa15cb1c987@googlemail.com>
Reviewed-by: Harald Alvestrand <ce816cd73d80f958d82de1df356058c2d2bca378@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#32802}

TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc