Update to v5.5 kernel headers.

Kernel headers coming from:

Git: https://android.googlesource.com/kernel/common/
Branch: android-mainline
Tag: android-mainline-5.5

Test: Boots on walleye.
Test: Ran bionic-unit-tests on walleye.
Test: Boots on cuttlefish.
Test: Ran bionic-unit-tests on cuttlefish.
Change-Id: I57387d3c31e0ba5ad125ffe291cecf365c7b374e
Merged-In: I57387d3c31e0ba5ad125ffe291cecf365c7b374e
diff --git a/libc/kernel/uapi/linux/magic.h b/libc/kernel/uapi/linux/magic.h
index ebbb58c..ca1daea 100644
--- a/libc/kernel/uapi/linux/magic.h
+++ b/libc/kernel/uapi/linux/magic.h
@@ -98,4 +98,5 @@
 #define ZSMALLOC_MAGIC 0x58295829
 #define DMA_BUF_MAGIC 0x444d4142
 #define Z3FOLD_MAGIC 0x33
+#define PPC_CMM_MAGIC 0xc7571590
 #endif