[Support][mips] Remove unnecessary includes from Memory.inc

The mips-specific includes have been unnecessary ever since the
__clear_cache() builtin replaced cacheflush().

Differential Revision: https://reviews.llvm.org/D111486

(cherry picked from commit a5de04d)

Author: vhankala

llvm/lib/Support/Unix/Memory.inc

@@ -29,14 +29,6 @@
 #include <zircon/syscalls.h>
 #endif
 
-#if defined(__mips__)
-#  if defined(__OpenBSD__)
-#    include <mips64/sysarch.h>
-#  elif !defined(__FreeBSD__)
-#    include <sys/cachectl.h>
-#  endif
-#endif
-
 #if defined(__APPLE__)
 extern "C" void sys_icache_invalidate(const void *Addr, size_t len);
 #else