staging: rtl8712: uninitialized memory in read_bbreg_hdl()

Colin King reported a bug in read_bbreg_hdl():

	memcpy(pcmd->rsp, (u8 *)&val, pcmd->rspsz);

The problem is that "val" is uninitialized.

This code is obviously not useful, but so far as I can tell
"pcmd->cmdcode" is never GEN_CMD_CODE(_Read_BBREG) so it's not harmful
either.  For now the easiest fix is to just call r8712_free_cmd_obj()
and return.

Fixes: 2865d42c

 ("staging: r8712u: Add the new driver to the mainline kernel")
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>