arm64: initialize pgprot info earlier in boot

Presently, paging_init() calls init_mem_pgprot() to initialize pgprot
values used by macros such as PAGE_KERNEL, PAGE_KERNEL_EXEC, etc.

The new fixmap and early_ioremap support also needs to use these macros
before paging_init() is called.  This patch moves the init_mem_pgprot()
call out of paging_init() and into setup_arch() so that pgprot_default
gets initialized in time for fixmap and early_ioremap.

Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Borislav Petkov <borislav.petkov@amd.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 0bf757c73d)
Signed-off-by: Mark Brown <broonie@linaro.org>

arch/arm64/include/asm/mmu.h

@@ -27,5 +27,6 @@ typedef struct {
 extern void paging_init(void);
 extern void setup_mm_for_reboot(void);
 extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt);
+extern void init_mem_pgprot(void);
 
 #endif

arch/arm64/kernel/setup.c

@@ -268,6 +268,8 @@ void __init setup_arch(char **cmdline_p)
 
 	*cmdline_p = boot_command_line;
 
+	init_mem_pgprot();
+
 	parse_early_param();
 
 	arm64_memblock_init();

arch/arm64/mm/mmu.c

@@ -125,7 +125,7 @@ early_param("cachepolicy", early_cachepolicy);
 /*
  * Adjust the PMD section entries according to the CPU in use.
  */
-static void __init init_mem_pgprot(void)
+void __init init_mem_pgprot(void)
 {
 	pteval_t default_pgprot;
 	int i;
@@ -357,7 +357,6 @@ void __init paging_init(void)
 {
 	void *zero_page;
 
-	init_mem_pgprot();
 	map_mem();
 
 	/*