core: don't divide by sizeof(*mem) for ddr nsec memory
core: don't divide by sizeof(*mem) for ddr nsec memory

Since the two addresses are already of type struct core_mmu_phys_mem, do
not divide by sizeof(struct core_mmu_phys_mem). This broke dynamic shared
memory on Juno r0, since nelem would be zero for two slots.

Tested on Juno r0.

Fixes: 2f82082fada3 ("core: add ddr overall register")
Reviewed-by: Jens Wiklander <7706914404370d7502c27a0eff493dcf491feb51@linaro.org>
Signed-off-by: Rouven Czerwinski <9e3b552020c3881dcdc7e109554acc5f29f3e8f9@czerwinskis.de>

pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os