staging: rtl8192u: rename variables in r819xU_phy.h

This patch renames the variables that were renamed in
r819xU_phy.c to preserve consistency between the two.

Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>