staging: rtl8192e: Remove unsupported modes IEEE_N_5G and IEEE_A

Remove unsupported modes IEEE_N_5G and IEEE_A as those are not supported
by hardware and are not offered by user software. Remove resulting dead
code and unused defines.

Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/40c5b21654376348144280dbe45203140c6e6807.1687007788.git.philipp.g.hortmann@gmail.com


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