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/usb/ch9.h b/libc/kernel/uapi/linux/usb/ch9.h
index 89d772a..2d69abd 100644
--- a/libc/kernel/uapi/linux/usb/ch9.h
+++ b/libc/kernel/uapi/linux/usb/ch9.h
@@ -380,6 +380,8 @@
 #define USB_BESL_SUPPORT (1 << 2)
 #define USB_BESL_BASELINE_VALID (1 << 3)
 #define USB_BESL_DEEP_VALID (1 << 4)
+#define USB_SET_BESL_BASELINE(p) (((p) & 0xf) << 8)
+#define USB_SET_BESL_DEEP(p) (((p) & 0xf) << 12)
 #define USB_GET_BESL_BASELINE(p) (((p) & (0xf << 8)) >> 8)
 #define USB_GET_BESL_DEEP(p) (((p) & (0xf << 12)) >> 12)
 } __attribute__((packed));