staging: rtl8188eu: cleanup declarations in rtw_pwrctrl.c

Replace tabs with spaces in declarations to cleanup whitespace.
Signed-off-by: Michael Straube <straube.linux@gmail.com>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Link: https://lore.kernel.org/r/20191123151635.155138-2-straube.linux@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>