package/igh-ethercat: bump to latest Git commit

The current version 1.5.2 dates back from 2013, so it is extremely
old. The latest master branch of igh-ethercat contains numerous fixes,
including fixes to ensure that it builds with recent Linux kernel
releases. Backporting the individual patches fixing those issues on a
9 year old release would be too much effort, so we propose to simply
bump the version to the latest available in the Git master branch.

Fixes:

  http://autobuild.buildroot.net/results/4dc9b71c805a8156bcf8f398edd3a30f2b6ac6da/



Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>