rtl8192u: promote auth_mode to a full 8 bits

Currently LEAP is defined to two locally but the identically named
global constant is 128 in <linux/ieee80211.h>.  In order for us to
switch over to using the global value, we need to adjust the local
storage which is currently not enough to hold the larger value.

This is now consistent with the similar struct used in
drivers/net/wireless/ipw2x00/libipw.h and other drivers.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>