init: consider all platform devices for find_platform_device

Certain platforms list their platform devices with a path other than
the current /devices or /devices/platform.  Additionally, sometimes
these paths are a platform device themselves.  An example are devices
with a path /devices/soc.0/... where /devices/soc.0 is also a platform
devices.

Instead of continuing to special case these path prefixes, we can
consider the entire path, given that no mmc or usb devices create
platform devices as subdevices, which they should not by their very
nature.

This keeps the symlinks for block devices named identically for
current platform devices and places them in /dev/block/<full path to
device> for devices in locations other than /devices or
/devices/platform, eg /dev/block/platform/soc.0/7824900.sdhci

This keeps the symlinks for character deviced named identically for
all cases.

Change-Id: Ifc8eedf1086db1826dbc8f7e96cdfcfa5da876b3