staging: rtl8821ae: Fix halbtc8192e2ant.c 'should it be static?' sparse warnings

In halbtc8192e2ant.c, fix all instances of the sparse warning:

warning: symbol 'xxx' was not declared. Should it be static?
Signed-off-by: NMark Einon <mark@einon.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>