staging: rtl8192e: rtl8192e: rtl_core: remove unused global variable

Remove unused global variable channels from rtl_core.c

Signed-off-by: Saurav Girepunje <saurav.girepunje@gmail.com>
Link: https://lore.kernel.org/r/20210807102232.6674-4-saurav.girepunje@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>