mvebu: Migrate uci config to new PCIe path

mvebu: Migrate uci config to new PCIe path

The name of the PCIe controller node in device tree changed between
kernel 4.9 and kernel 4.14. Migrate the configuration when an update
from kernel 4.9 to 4.14 or back is done to the new name to make
the existing wifi configuration compatible with the new names.

This replaces the "pcie-controller" part with "pcie" on all nodes if the
file exists in sys fs.

This is not done in the uci-defualts, because they are getting executed
to late in the boot process. The kernel module gets loaded before the
uci-defaults scripts are executed. When the mwlwifi driver gets loaded
it will trigger an event via hotplug to detect new devices and as the
paths are not in the uci configuration they will be added again.
When the migration is done before the script will detect that they are
already there.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>