rtl8180: make sure RTL818X_MSR_ENEDCA is set for rtl8187se

MSR register for rtl8187se must always have ENEDCA flag set.
Write it accordingly when updated on BSS change.

Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>