lib: sbi: error handling in fdt_reset_init()

The initialization of a reset driver may fail for various reasons, like
a PMIC based reset driver not finding the required I2C driver. The return
code of the init routine may take other error values than -ENODEV.

If the initialization of a reset driver fails, this should not lead to the
board hanging. It is enough that the reset driver does not call
sbi_system_reset_add_device() to avoid invoking the driver for a device
that could not be initialized.

Change the return type of fdt_reset_init() to void.
Print a message if an error occurs.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Dong Du <Dd_nirvana@sjtu.edu.cn>
Reviewed-by: Anup Patel <anup.patel@wdc.com>