package/dtc: backport upstream fix solving Assertion Error with some .dts files

The build of U-Boot on Microchip (formerly Atmel) platforms currently
fails to build with an Assertion Error in dtc. This happens since we
bumped dtc from 1.4.4 to 1.4.7, as a regression was introduced in dtc
1.4.6, and fixed post-1.4.7. This commit backports the upstream commit
to resolve this Assertion Error.

The build error was:

dtc: livetree.c:438: propval_cell: Assertion `prop->val.len == sizeof(cell_t)' failed.
dtc: livetree.c:438: propval_cell: Assertion `prop->val.len == sizeof(cell_t)' failed.
Aborted (core dumped)

Fixes:

  https://gitlab.com/buildroot.org/buildroot/-/jobs/124434438


  (and numerous other similar build failures)

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>