staging: wimax: delete from the tree.

staging: wimax: delete from the tree.

As stated in f54ec58fee83 ("wimax: move out to staging"), the wimax code
is dead with no known users.  It has stayed in staging for 5 months,
with no one willing to take up the codebase for maintance and support,
so let's just remove it entirely for now.

If someone comes along and wants to revive it, a simple revert of this
patch is a good place to start.

Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Wang Hai <wanghai38@huawei.com>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Anirudh Rayabharam <mail@anirudhrb.com>
Cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: Hemansh Agnihotri <hemanshagnihotri27@gmail.com>
Cc: Ayush <ayush@disroot.org>
Cc: Xin Tan <tanxin.ctf@gmail.com>
Cc: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Cc: Shannon Nelson <snelson@pensando.io>
Link: https://lore.kernel.org/r/20210318093315.694404-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>