xenalyze: handle scheduling events

xenalyze: handle scheduling events

so the trace will show properly decoded info,
rather than just a bunch of hex codes.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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Cc: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Olaf Hering <olaf@aepfle.de>
---
Changes from v1:
 * SCHED_DOM_{ADD,REM} handling slightly changed, to avoid
   confusion with DOM0_DOM_{ADD,REM} (introduced later in
   the series);
 * '} * r =' turned into '} *r =', as requested
   during review.