core: mobj_reg_shm_free() using mobj_reg_shm_put()
core: mobj_reg_shm_free() using mobj_reg_shm_put()

Let reg_shm MOBJs be completely reference counted meaning that
mobj_free() on a reg_shm MOBJ only decrease the reference counter and
only free it if it reaches 0.

Reviewed-by: Etienne Carriere <f21bc5b8f3ea1962eb45af359f1abea6578cab94@linaro.org>
Signed-off-by: Jens Wiklander <7706914404370d7502c27a0eff493dcf491feb51@linaro.org>

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