MIPS: dts: lantiq: Remove bogus interrupt-parent; line

Specifying interrupt-parent without a value (in other words, as a bool)
doesn't really mean anything. Remove one such property in the Lantiq
Danube DT, at /sram@1f000000/eiu@101000.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>