staging: rtl8188eu: remove write-only power struct component

pwrpriv->bFwCurrentInPSMode is initialized and updated but nobody reads
its value. Remove this write-only component.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20210725155902.32433-10-martin@kaiser.cx


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