nimble/host: Fix may be uninitialize warning
nimble/host: Fix may be uninitialize warning

Seems like spurious error, but according to GCC "duration_ticks" may be
uninitialized if os_time_ms_to_ticks() is static inline...

apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble