arm: Implement show_boot_progress() for imx53's HSC and DDC devices

arm: Implement show_boot_progress() for imx53's HSC and DDC devices

This patch provides information regarding the boot stage with using LEDs.
On the very beginning of U-Boot execution the GREEN LED is turned on.
When the execution is passed to Linux kernel the GREEN LED is off and
RED one is ON.

Afterwards, when Linux takes over the execution, the "heartbeat" driver
provides indication if the board is still alive.

Please also note that this patch uses {set|clr}bits_le32 macros as turning
ON GREEN LED is performed in a _very_ early stage of U-Boot execution
before DM_GPIOs are initialized.

Signed-off-by: Lukasz Majewski <lukma@denx.de>