riscv: module: Allocate PLT entries for R_RISCV_PLT32

apply_r_riscv_plt32_rela() may need to emit a PLT entry for the
referenced symbol, so there must be space allocated in the PLT.

Fixes: 8fd6c514 ("riscv: Add remaining module relocations")
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20250409171526.862481-2-samuel.holland@sifive.com


Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>