drm/i915/perf: Fix compiler warning for string truncation

drivers/gpu/drm/i915/i915_oa_cnl.c: In function ‘i915_perf_load_test_config_cnl’:
drivers/gpu/drm/i915/i915_oa_cnl.c:99:2: error: ‘strncpy’ output truncated before terminating nul copying 36 bytes from a string of the same length [-Werror=stringop-truncation]

v2: strlcpy

Fixes: 95690a02

 ("drm/i915/perf: enable perf support on CNL")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180208102403.5587-2-chris@chris-wilson.co.uk