The recent introduction of relocatable kernels prepared the move of
.rela.dyn to the init section, but actually forgot to do so, so do it
here.

Before this patch: "Freeing unused kernel image (initmem) memory: 2592K"
After this patch:  "Freeing unused kernel image (initmem) memory: 6288K"

The difference corresponds to the size of the .rela.dyn section:
"[42] .rela.dyn         RELA             ffffffff8197e798  0127f798
       000000000039c660  0000000000000018   A      47     0     8"

Fixes: 559d1e45 ("riscv: Use --emit-relocs in order to move .rela.dyn in init")
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20230428120932.22735-1-alexghiti@rivosinc.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>