staging: rtl8188eu: fix spaces instead of tabs for rtw_recv.c

This commit fixes the following checkpatch errors:

rtl8188eu/core/rtw_recv.c
    - 1874: ERROR: code indent should use tabs where possible

Signed-off-by: Konrad Zapalowicz <bergo.torino@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>