net: lwm2m: fix buffer length check in lwm2m_engine_set

Previously, lwm2m_engine set would check against the max_data_len
parameter of the ressource, but didn't take into consideration the
(possibly changed) max_data_len returned by the pre_write callback.

Fixes #30541

Signed-off-by: Henning Fleddermann <henning.fleddermann@grandcentrix.net>
1 file changed