Revert "soc: imx: imx8m-blk-ctrl: set power device name"

This reverts commit 8239d67f.

This change confuses the sysfs cleanup path since the rename is done
after the device registration.

Fixes: 8239d67f ("soc: imx: imx8m-blk-ctrl: set power device name")
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>