Update to v4.17.3 kernel headers.

Test: Builds, boots on a walleye.
Change-Id: I389d8b61ec00ea309e38d1b1a2e0dace48c21edb
diff --git a/libc/kernel/uapi/linux/i2c.h b/libc/kernel/uapi/linux/i2c.h
index bb8f4f5..dc1e96a 100644
--- a/libc/kernel/uapi/linux/i2c.h
+++ b/libc/kernel/uapi/linux/i2c.h
@@ -24,6 +24,7 @@
   __u16 flags;
 #define I2C_M_RD 0x0001
 #define I2C_M_TEN 0x0010
+#define I2C_M_DMA_SAFE 0x0200
 #define I2C_M_RECV_LEN 0x0400
 #define I2C_M_NO_RD_ACK 0x0800
 #define I2C_M_IGNORE_NAK 0x1000