drm/xe/observation: Drop empty sysctl table entry

An empty sysctl table entry was inadvertently left behind for observation
sysctl. The breaks on 6.11 with the following errors:

[  219.654850] sysctl table check failed: dev/xe/(null) procname is null
[  219.654862] sysctl table check failed: dev/xe/(null) No proc_handler

Drop the empty entry.

Fixes: 63347fe0

 ("drm/xe/uapi: Rename xe perf layer as xe observation layer")
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2419
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240805062057.3547560-1-ashutosh.dixit@intel.com
(cherry picked from commit be1dec570b6f5a29ce9c99334c52bea94c28914b)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>