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/input-event-codes.h b/libc/kernel/uapi/linux/input-event-codes.h
index 5d20c24..0230c11 100644
--- a/libc/kernel/uapi/linux/input-event-codes.h
+++ b/libc/kernel/uapi/linux/input-event-codes.h
@@ -691,7 +691,10 @@
 #define SW_LINEIN_INSERT 0x0d
 #define SW_MUTE_DEVICE 0x0e
 #define SW_PEN_INSERTED 0x0f
-#define SW_MAX 0x0f
+#define SW_HPHL_OVERCURRENT 0x10
+#define SW_HPHR_OVERCURRENT 0x11
+#define SW_UNSUPPORT_INSERT 0x12
+#define SW_MAX 0x20
 #define SW_CNT (SW_MAX + 1)
 #define MSC_SERIAL 0x00
 #define MSC_PULSELED 0x01