staging: rtl8192u: Remove typedef for struct _RT_LINK_DETECT_T

-Avoid typedefs for structure types to maintain kernel coding style.
-Remove typedefs RT_LINK_DETECT_T and *PRT_LINK_DETECT_T of struct _RT_LINK_DETECT_T.
-Change Structure name _RT_LINK_DETECT_T to rt_link_detect to maintain Linux kernel Coding Style.
-Replace occurence of RT_LINK_DETECT_T to struct rt_link_detect.

Signed-off-by: Bhanusree Pola <bhanusreemahesh@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>