The crashkernel memory has been allocated successfully, whereas
it failed to insert into iomem_resource. This is due to the
unique reserving logic in risc-v arch specific code, i.e.
crashk_res/crashk_low_res will be added into iomem_resource
later in init_resources(), which is not aligned with current
unified reserving logic in reserve_crashkernel_{generic,low}()
and therefore leads to the failure of crashkernel reservation.
Removing the arch specific code within #ifdef CONFIG_KEXEC_CORE
in init_resources() to fix above problem.