staging: r8188eu: Drop get_recvframe_data()

staging: r8188eu: Drop get_recvframe_data()

When building with -Warray-bounds, the following warning is emitted:

In file included from ./include/linux/string.h:253,
                 from ./arch/x86/include/asm/page_32.h:22,
                 from ./arch/x86/include/asm/page.h:14,
                 from ./arch/x86/include/asm/thread_info.h:12,
                 from ./include/linux/thread_info.h:60,
                 from ./arch/x86/include/asm/preempt.h:7,
                 from ./include/linux/preempt.h:78,
                 from ./include/linux/rcupdate.h:27,
                 from ./include/linux/rculist.h:11,
                 from ./include/linux/sched/signal.h:5,
                 from ./drivers/staging/rtl8723bs/include/drv_types.h:17,
                 from drivers/staging/rtl8723bs/core/rtw_recv.c:7:
In function 'memcpy',
    inlined from 'wlanhdr_to_ethhdr' at drivers/staging/rtl8723bs/core/rtw_recv.c:1554:2:
./include/linux/fortify-string.h:41:33: warning: '__builtin_memcpy' offset [0, 5] is out of the bounds [0, 0] [-Warray-bounds]
   41 | #define __underlying_memcpy     __builtin_memcpy
      |                                 ^

This is because the compiler sees it is possible for "ptr" to be a NULL
value, and concludes that it has zero size and attempts to copy to it
would overflow. Instead, remove the get_recvframe_data() entirely, as
it's not possible for this to ever be NULL.

Additionally add missing NULL checks after recvframe_pull() (which are
present in the rtl8712 driver).

Cc: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Phillip Potter <phil@philpotter.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Michael Straube <straube.linux@gmail.com>
Cc: Fabio Aiuto <fabioaiuto83@gmail.com>
Cc: linux-staging@lists.linux.dev
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220118193327.2822099-2-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>