extable relies on the MMU to work properly, so it's useless to
include __ex_table sections and build extable related functions for
!MMU case.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Link: https://lore.kernel.org/r/20230509152641.805-1-jszhang@kernel.orgSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>