Update to v5.8 kernel headers.

Kernel headers coming from:

Git: https://android.googlesource.com/kernel/common/
Branch: android-mainline
Tag: android-mainline-5.8

Test: NA
Change-Id: I2231c877589820fc09800a200cf4ac62ba74b04c
diff --git a/libc/kernel/uapi/linux/fb.h b/libc/kernel/uapi/linux/fb.h
index 38da042..a0ef0c4 100644
--- a/libc/kernel/uapi/linux/fb.h
+++ b/libc/kernel/uapi/linux/fb.h
@@ -182,6 +182,7 @@
 #define FB_ACTIVATE_ALL 64
 #define FB_ACTIVATE_FORCE 128
 #define FB_ACTIVATE_INV_MODE 256
+#define FB_ACTIVATE_KD_TEXT 512
 #define FB_ACCELF_TEXT 1
 #define FB_SYNC_HOR_HIGH_ACT 1
 #define FB_SYNC_VERT_HIGH_ACT 2