Drop always off CONFIG_WIFI_TEST option
Option PLATFORM_LINUX is always on

Also remove a layer of indirection for rsprintf
Remove always off CONFIG_PLATFORM_SPRD option
Remove always off PLATFORM_MPIXEL option
Remove DBG_MEMORY_LEAK specific code
Remove DBG_DELAY_OS specific code
Remove support for old versions of the kernel
Remove always off CONFIG_EASY_REPLACEMENT option
Remove always off CONFIG_NO_WIRELESS_HANDLERS option
Remove always off DBG_MEM_ALLOC option
Remove always off DBG_IO option
Remove rtw_vmalloc function
Remove unused rtw_get_current_time()
Remove unused rtw_get_passing_time_ms()