riscv: Fix relocation_hashtable size

riscv: Fix relocation_hashtable size

A second dereference is needed to get the accurate size of the
relocation_hashtable.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Fixes: d8792a5734b0 ("riscv: Safely remove entries from relocation list")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Julia Lawall <julia.lawall@inria.fr>
Closes: https://lore.kernel.org/r/202312120044.wTI1Uyaa-lkp@intel.com/
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/20240104-module_loading_fix-v3-3-a71f8de6ce0f@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>