arm64: unexport set_memory_x and set_memory_nx

No module currently messed with clearing or setting the execute
permission of kernel memory, and none really should.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Will Deacon <will@kernel.org>

arch/arm64/mm/pageattr.c

@@ -128,7 +128,6 @@ int set_memory_nx(unsigned long addr, int numpages)
 					__pgprot(PTE_PXN),
 					__pgprot(0));
 }
-EXPORT_SYMBOL_GPL(set_memory_nx);
 
 int set_memory_x(unsigned long addr, int numpages)
 {
@@ -136,7 +135,6 @@ int set_memory_x(unsigned long addr, int numpages)
 					__pgprot(0),
 					__pgprot(PTE_PXN));
 }
-EXPORT_SYMBOL_GPL(set_memory_x);
 
 int set_memory_valid(unsigned long addr, int numpages, int enable)
 {