staging:rtl8712: replace cap_* definitions with native kernel WLAN_CAPABILITY_*

cap_* definitions duplicate WLAN_CAPABILITY_*. Remove cap_* definitions,
improve code consistency.

Reviewed-by: Mike Ximing Chen <mike.ximing.chen@intel.com>
Signed-off-by: Ivan Safonov <insafonov@gmail.com>
Link: https://lore.kernel.org/r/20210227222236.581490-5-insafonov@gmail.com


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