[net][sal] Remove SAL_USING_POSIX dependence for lwIP stack.
#error "POSIX poll/select, stdin need file system(RT_USING_DFS) and device file system(RT_USING_DFS_DEVFS)"
#endif
-#if defined(RT_USING_LWIP) && !defined(SAL_USING_POSIX)
-#error "POSIX poll/select, stdin need file BSD socket API(SAL_USING_POSIX)"
-#endif
-
#if !defined(RT_USING_LIBC)
#error "POSIX layer need standard C library(RT_USING_LIBC)"
#endif
