riscv: Move EXCEPTION_TABLE to RO_DATA segment

_ex_table section is read-only, so move it to RO_DATA.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/kernel/vmlinux-xip.lds.S

@@ -121,7 +121,6 @@ SECTIONS
 	}
 
 	BSS_SECTION(PAGE_SIZE, PAGE_SIZE, 0)
-	EXCEPTION_TABLE(0x10)
 
 	.rel.dyn : AT(ADDR(.rel.dyn) - LOAD_OFFSET) {
 		*(.rel.dyn*)

arch/riscv/kernel/vmlinux.lds.S

@@ -4,6 +4,8 @@
  * Copyright (C) 2017 SiFive
  */
 
+#define RO_EXCEPTION_TABLE_ALIGN	16
+
 #ifdef CONFIG_XIP_KERNEL
 #include "vmlinux-xip.lds.S"
 #else
@@ -112,8 +114,6 @@ SECTIONS
 		*(.srodata*)
 	}
 
-	EXCEPTION_TABLE(0x10)
-
 	. = ALIGN(SECTION_ALIGN);
 	_data = .;