gpio-cdev: provide HASH values for nu801

Chen Minqiang reported that he has troubles downloading nu801.
His logs showed the followin TLS Handshake failure.

|Checking out files from the git repository...
|Cloning into 'nu801-d9942c0c'...
|fatal: unable to access 'https://github.com/chunkeey/nu801.git/':
|  gnutls_handshake() failed: The TLS connection was non-properly terminated.
|Makefile:39: recipe for target '[...]/dl/nu801-d9942c0c.tar.xz' failed

This can be fixed by providing a PKG_MIRROR_HASH. The download
scripts will now be able to pull the source from OpenWrt's source
archive, which should be available through HTTP.

Reported-by: Chen Minqiang <ptpt52@gmail.com>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>

package/system/gpio-cdev/nu801/Makefile

@@ -8,7 +8,7 @@ PKG_RELEASE:=1
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL:=https://github.com/chunkeey/nu801.git
 PKG_SOURCE_VERSION:=d9942c0ceb949080b93366a9431028de3608e535
-
+PKG_MIRROR_HASH:=859be7dec96d2a0d6ee8b80c6f1a703384940d19caeeb74a4ac0a961b2a985db
 PKG_MAINTAINER:=Christian Lamparter <chunkeey@gmail.com>
 PKG_LICENSE:=GPL-3.0-or-later
 PKG_LICENSE_FILES:=LICENSE