RISC-V: Add the directive for alignment of stvec's value

The stvec's value must be 4 byte alignment by specification definition.
These directives avoid to stvec be set the non-alignment value.

Signed-off-by: Zong Li <zong@andestech.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
1 file changed