treewide: Add a function to change page permissions

For armv8 we are adding proper page permissions for the relocated U-Boot
binary. Add a weak function that can be used across architectures to change
the page permissions

Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on AML-S905X-CC
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/arch/riscv/lib/cache.c b/arch/riscv/lib/cache.c
index 71e4937..31aa30b 100644
--- a/arch/riscv/lib/cache.c
+++ b/arch/riscv/lib/cache.c
@@ -8,6 +8,7 @@
 #include <dm.h>
 #include <asm/insn-def.h>
 #include <linux/const.h>
+#include <linux/errno.h>
 
 #define CBO_INVAL(base)						\
 	INSN_I(OPCODE_MISC_MEM, FUNC3(2), __RD(0),		\
@@ -151,3 +152,8 @@
 	if (!zicbom_block_size)
 		log_debug("Zicbom not initialized.\n");
 }
+
+int __weak pgprot_set_attrs(phys_addr_t addr, size_t size, enum pgprot_attrs perm)
+{
+	return -ENOSYS;
+}