MIPS: Remove __invalidate_kernel_vmap_range

The __invalidate_kernel_vmap_range function pointer global variable
isn't used anywhere. Remove it.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: trivial@kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/17174/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/mm/cache.c

@@ -45,7 +45,6 @@ void (*__flush_cache_vunmap)(void);
 
 void (*__flush_kernel_vmap_range)(unsigned long vaddr, int size);
 EXPORT_SYMBOL_GPL(__flush_kernel_vmap_range);
-void (*__invalidate_kernel_vmap_range)(unsigned long vaddr, int size);
 
 /* MIPS specific cache operations */
 void (*flush_cache_sigtramp)(unsigned long addr);