staging: rtl8712: Remove driver using deprecated API wext

staging: rtl8712: Remove driver using deprecated API wext

This driver is in the staging area since 2010.

The following reasons lead to the removal:
- This driver generates maintenance workload for itself and for API wext
- A MAC80211 driver was available in 2016 time frame; This driver does
  not compile anymore but would be a better starting point than the
  current driver. Here the note from the TODO file:
  A replacement for this driver with MAC80211 support is available
  at https://github.com/chunkeey/rtl8192su
- no progress changing to mac80211
- Using this hardware is security wise not state of the art as WPA3 is
  not supported.

The longterm kernels will still support this hardware for years.

Find further discussions in the Link below.

Link: https://lore.kernel.org/linux-staging/a02e3e0b-8a9b-47d5-87cf-2c957a474daa@gmail.com/T/#t
Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Tested-by: Dominik Karol Piątkowski <dominik.karol.piatkowski@protonmail.com>
Link: https://lore.kernel.org/r/20241020144933.10956-1-philipp.g.hortmann@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>