riscv: Fix default misaligned access trap

Commit d1703dc7 ("RISC-V: Detect unaligned vector accesses
supported") removed the default handlers for handle_misaligned_load()
and handle_misaligned_store(). When the kernel is compiled without
RISCV_SCALAR_MISALIGNED, these handlers are never defined, causing
compilation errors.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Fixes: d1703dc7 ("RISC-V: Detect unaligned vector accesses supported")
Reviewed-by: Jesse Taube <mr.bossman075@gmail.com>
Link: https://lore.kernel.org/r/20241108-fix_handle_misaligned_load-v2-1-91d547ce64db@rivosinc.com


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>