drm/msm: Make enable_eviction flag static

No need for it to be visible outside of this one src file.
Signed-off-by: Rob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/491219/
Link: https://lore.kernel.org/r/20220625225454.81039-3-robdclark@gmail.com

drivers/gpu/drm/msm/msm_gem_shrinker.c

@@ -15,7 +15,7 @@
 /* Default disabled for now until it has some more testing on the different
  * iommu combinations that can be paired with the driver:
  */
-bool enable_eviction = false;
+static bool enable_eviction = false;
 MODULE_PARM_DESC(enable_eviction, "Enable swappable GEM buffers");
 module_param(enable_eviction, bool, 0600);