Update to kernel headers v4.12.3.

Test: Built angler.
Change-Id: Icbcf4fac2334de8409b049ed7a3b4c24b4e98ce9
diff --git a/libc/kernel/uapi/drm/msm_drm.h b/libc/kernel/uapi/drm/msm_drm.h
index a8e4943..83ad769 100644
--- a/libc/kernel/uapi/drm/msm_drm.h
+++ b/libc/kernel/uapi/drm/msm_drm.h
@@ -37,6 +37,7 @@
 #define MSM_PARAM_CHIP_ID 0x03
 #define MSM_PARAM_MAX_FREQ 0x04
 #define MSM_PARAM_TIMESTAMP 0x05
+#define MSM_PARAM_GMEM_BASE 0x06
 struct drm_msm_param {
   __u32 pipe;
   __u32 param;