staging: rtl8712: Fix multiple line dereference

This patch fixes the following warning in rtl871x_mlme.c

WARNING: Avoid multiple line dereference - prefer 'adapter->securitypriv.PrivacyAlgrthm'

Signed-off-by: Shibo Li <zzutcyha@163.com>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> AW-NU120
Reviewed-by: Dan Carpenter <error27@gmail.com>
Link: https://lore.kernel.org/r/20230220084050.18459-1-zzutcyha@163.com


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