drm/i915/perf: add sentinel to xehp_oa_b_counters

Arrays passed to reg_in_range_table should end with empty record.

The patch solves KASAN detected bug with signature:
BUG: KASAN: global-out-of-bounds in xehp_is_valid_b_counter_addr+0x2c7/0x350 [i915]
Read of size 4 at addr ffffffffa1555d90 by task perf/1518

CPU: 4 PID: 1518 Comm: perf Tainted: G U 6.4.0-kasan_438-g3303d06107f3+ #1
Hardware name: Intel Corporation Meteor Lake Client Platform/MTL-P DDR5 SODIMM SBS RVP, BIOS MTLPFWI1.R00.3223.D80.2305311348 05/31/2023
Call Trace:
<TASK>
...
xehp_is_valid_b_counter_addr+0x2c7/0x350 [i915]

Fixes: 0fa9349d

 ("drm/i915/perf: complete programming whitelisting for XEHPSDV")
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230711153410.1224997-1-andrzej.hajda@intel.com