dts: gen_defines.py: Do not crash on 'type: path' properties

'type: path' was added to edtlib for completeness in commit 23a5b496
("dts: edtlib: Add 'type: path' for path references"). gen_defines.py
crashes if it's ever used though, because it gets confused for a
'type: phandle-array'.

Ignore 'type: path' properties in gen_defines.py, like how
'type: phandle' and 'type: phandles' are currently ignored too.

(Note that gen_defines.py is only one possible user of edtlib.)

Fixes: #22197

Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>