Check if gARMPagingMethod is null

in arch_vm_translation_map_is_kernel_page_accessible. Fix borrowed from x86
(commit 428b9e758c).

Signed-off-by: Adrien Destugues <[email protected]>

Fixes #11107.

src/system/kernel/arch/arm/arch_vm_translation_map.cpp

@@ -145,5 +145,8 @@ bool
 arch_vm_translation_map_is_kernel_page_accessible(addr_t virtualAddress,
 	uint32 protection)
 {
+	if(!gARMPagingMethod)
+		return true;
+
 	return gARMPagingMethod->IsKernelPageAccessible(virtualAddress, protection);
 }