lib: Add misaligned load/store trap handling

We generally don't get misaligned load/store traps from Linux/U-Boot
compiled using GCC 8.2 or higher but this is not true with older
GCC toolchains. To tackle this we add misaligned load/store trap
handling adopted from BBL sources but much more simpler.
(Note: BBL sources can be found at https://github.com/riscv/riscv-pk.git)

Signed-off-by: Anup Patel <anup.patel@wdc.com>

lib/objects.mk

@@ -18,6 +18,7 @@ lib-objs-y += sbi_hart.o
 lib-objs-y += sbi_illegal_insn.o
 lib-objs-y += sbi_init.o
 lib-objs-y += sbi_ipi.o
+lib-objs-y += sbi_misaligned_ldst.o
 lib-objs-y += sbi_system.o
 lib-objs-y += sbi_timer.o
 lib-objs-y += sbi_trap.o