Disable SoftAP config backup and restore on Wear

SoftAP config restore has caused various bugs during Wear OOBE (e.g.
b/276411509, b/269598544). SoftAP is used for WiFi hotspot, which no
Wear OEM supports AFAIK.

Bug: 276411509
Test: manually flashed to watch, 'Restored soft ap backup data' not logged
Change-Id: I884e71d0353d6f7eb3bb66c2aec4734aa40f5def
(cherry picked from commit a5a9fd330d65035c3ad4ee706ae8abaeabbd7533)