Update to android-mainline kernel headers v5.4.

Update generate_uapi_headers.sh to checkout the android mainline
kernel. Also, add a small modification to look for the kernel directory
in common not linux-stable.

Remove deprecated android headers from android/uapi/linux. Also,
remove f_accessory.h since it's in the android mainline kernel.

Test: Builds and runs on walleye.
Change-Id: Ia371305e19f56e6bcc2db6d5b4d299819f07ffc6
diff --git a/libc/kernel/uapi/linux/sctp.h b/libc/kernel/uapi/linux/sctp.h
index 18c5d21..9a808ef 100644
--- a/libc/kernel/uapi/linux/sctp.h
+++ b/libc/kernel/uapi/linux/sctp.h
@@ -87,6 +87,9 @@
 #define SCTP_INTERLEAVING_SUPPORTED 125
 #define SCTP_SENDMSG_CONNECT 126
 #define SCTP_EVENT 127
+#define SCTP_ASCONF_SUPPORTED 128
+#define SCTP_AUTH_SUPPORTED 129
+#define SCTP_ECN_SUPPORTED 130
 #define SCTP_PR_SCTP_NONE 0x0000
 #define SCTP_PR_SCTP_TTL 0x0010
 #define SCTP_PR_SCTP_RTX 0x0020