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/nvme_ioctl.h b/libc/kernel/uapi/linux/nvme_ioctl.h
index 10d8b8f..f2a328e 100644
--- a/libc/kernel/uapi/linux/nvme_ioctl.h
+++ b/libc/kernel/uapi/linux/nvme_ioctl.h
@@ -53,6 +53,27 @@
   __u32 timeout_ms;
   __u32 result;
 };
+struct nvme_passthru_cmd64 {
+  __u8 opcode;
+  __u8 flags;
+  __u16 rsvd1;
+  __u32 nsid;
+  __u32 cdw2;
+  __u32 cdw3;
+  __u64 metadata;
+  __u64 addr;
+  __u32 metadata_len;
+  __u32 data_len;
+  __u32 cdw10;
+  __u32 cdw11;
+  __u32 cdw12;
+  __u32 cdw13;
+  __u32 cdw14;
+  __u32 cdw15;
+  __u32 timeout_ms;
+  __u32 rsvd2;
+  __u64 result;
+};
 #define nvme_admin_cmd nvme_passthru_cmd
 #define NVME_IOCTL_ID _IO('N', 0x40)
 #define NVME_IOCTL_ADMIN_CMD _IOWR('N', 0x41, struct nvme_admin_cmd)
@@ -61,4 +82,6 @@
 #define NVME_IOCTL_RESET _IO('N', 0x44)
 #define NVME_IOCTL_SUBSYS_RESET _IO('N', 0x45)
 #define NVME_IOCTL_RESCAN _IO('N', 0x46)
+#define NVME_IOCTL_ADMIN64_CMD _IOWR('N', 0x47, struct nvme_passthru_cmd64)
+#define NVME_IOCTL_IO64_CMD _IOWR('N', 0x48, struct nvme_passthru_cmd64)
 #endif