drm/xe/exec: Fix minor bug related to xe_sync_entry_cleanup

drm/xe/exec: Fix minor bug related to xe_sync_entry_cleanup

Increment num_syncs after xe_sync_entry_parse() is successful to ensure
the xe_sync_entry_cleanup() logic under "err_syncs" label works correctly.

v2: Use the same pattern as that in xe_vm.c (Matt Brost)

Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240711211203.3728180-1-ashutosh.dixit@intel.com
(cherry picked from commit 43a6faa6d9b5e9139758200a79fe9c8f4aaa0c8d)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>