staging: rtl8192e: Remove entry .nic_type from struct rtl819x_ops

Remove unchanged entry .nic_type and replace it with constant NIC_8192E.
This increases readability of the code.

Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/f1fd37a2d2b90bef8caac31a98f3eeff404b3095.1677010997.git.philipp.g.hortmann@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>