staging: rtl8723bs: remove unused variables and code block left unused in os_dep...

staging: rtl8723bs: remove unused variables and code block left unused in os_dep/ioctl_linux.c

fix following kernel test robot warnings:

drivers/staging/rtl8723bs/os_dep/ioctl_linux.c:
In function ‘rtw_dbg_port’:
drivers/staging/rtl8723bs/os_dep/ioctl_linux.c:2548:33:
warning: variable ‘preorder_ctrl’ set but
	not used [-Wunused-but-set-variable]
       struct recv_reorder_ctrl *preorder_ctrl;
                                 ^~~~~~~~~~~~~

remove also unnecessary conditional code block.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Fabio Aiuto <fabioaiuto83@gmail.com>
Link: https://lore.kernel.org/r/0e950e74565b573a98b851092cc2078045d5ac3d.1617962215.git.fabioaiuto83@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>