wasapi: Fix double call to Start when resetting the element

When either the source or sink goes from PLAYING -> NULL -> PLAYING,
we call _reset() which sets client_needs_restart, and then we call
prepare() which calls IAudioClient_Start(), so we don't need to call
it again in src_read() or sink_write(). Unlike when we're just going
PLAYING -> PAUSED -> PLAYING.
6 jobs for fix-wasapi-double-start in 27 minutes and 11 seconds
Status Job ID Name Coverage
  Preparation
passed #73251
gst indent

00:00:33

passed #73250
manifest

00:00:23

 
  Build
passed #73252
build fedora x86_64

00:02:55

 
  Test
passed #73253
check fedora

00:15:32

 
  Full Builds
passed #73254
build android arm64 api28

00:03:56

passed #73255
build cerbero fedora x86_64

00:08:10