Until this patch was rpmb_dev_register() always freeing rdev in the error
path. However, past device_register() it must not do that since the memory
is now managed by the device even if it failed to register properly. So fix
this by doing a put_device() before returning the error code.

Fixes the smatch warning:
        drivers/misc/rpmb-core.c:204 rpmb_dev_register()
        warn: freeing device managed memory (leak): 'rdev'

Fixes: 1e9046e3 ("rpmb: add Replay Protected Memory Block (RPMB) subsystem")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Link: https://lore.kernel.org/r/20240902105803.2885544-1-jens.wiklander@linaro.orgSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>