dm: core: Respect drivers with the DM_FLAG_PRE_RELOC flag in lists_bind_fdt()

dm: core: Respect drivers with the DM_FLAG_PRE_RELOC flag in lists_bind_fdt()

Currently the comments of several APIs (eg: dm_init_and_scan()) say:

@pre_reloc_only: If true, bind only drivers with the DM_FLAG_PRE_RELOC
flag. If false bind all drivers.

The 'Pre-Relocation Support' chapter in doc/driver-model/README.txt
documents the same that both device tree properties and driver flag
are supported.

However the implementation only checks these special device tree
properties without checking the driver flag at all. This updates
lists_bind_fdt() to consider both scenarios.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Squashed in http://patchwork.ozlabs.org/patch/996473/ :
Signed-off-by: Simon Glass <sjg@chromium.org>