package/rtl8821cu: switch to version 20210916

The author of the 8821cu repository has requested that we switch to a newer
major version of the driver located at 8821cu-20210916:

https://github.com/morrownr/8821cu-20210118/pull/93#issuecomment-1452675897

Switch to that new repository.

Fixes a build issue against PowerPC64.

Signed-off-by: Christian Stewart <christian@paral.in>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/rtl8821cu/rtl8821cu.hash

@@ -1,3 +1,3 @@
 # Locally calculated
-sha256  09b9fb4160003502d564d0d0d85d6f19b8b6d1627d1a339b3ddfca6a948d84fb  rtl8821cu-86cc5ceb7c28b9b997838e1c796847f6c395c382.tar.gz
+sha256  1d090da292c3f9322603846467a80278670211fcde3354dcabfe32c449992493  rtl8821cu-69c903b75bde36293c66b25c051916a74dbadf58.tar.gz
 sha256  af54d00efc57cfce664171ac8be2a20c0f290b1b5c1a67bb2eba7b6380276c4e  LICENSE

package/rtl8821cu/rtl8821cu.mk

@@ -4,8 +4,8 @@
 #
 ################################################################################
 
-RTL8821CU_VERSION = 86cc5ceb7c28b9b997838e1c796847f6c395c382
-RTL8821CU_SITE = $(call github,morrownr,8821cu-20210118,$(RTL8821CU_VERSION))
+RTL8821CU_VERSION = 69c903b75bde36293c66b25c051916a74dbadf58
+RTL8821CU_SITE = $(call github,morrownr,8821cu-20210916,$(RTL8821CU_VERSION))
 RTL8821CU_LICENSE = GPL-2.0
 RTL8821CU_LICENSE_FILES = LICENSE