scripts/dtc: Update to upstream version v1.6.0-31-gcbca977ea121

scripts/dtc: Update to upstream version v1.6.0-31-gcbca977ea121

This adds the following commits from upstream:

cbca977ea121 checks: Allow PCI bridge child nodes without an address
73e0f143b73d libfdt: fdt_strerror(): Fix comparison warning
6c2be7d85315 libfdt: fdt_get_string(): Fix sequential write comparison warnings
82525f41d59e libfdt: libfdt_wip: Fix comparison warning
fb1f65f15832 libfdt: fdt_create_with_flags(): Fix comparison warning
f28aa271000b libfdt: fdt_move(): Fix comparison warnings
3d7c6f44195a libfdt: fdt_add_string_(): Fix comparison warning
10f682788c30 libfdt: fdt_node_offset_by_phandle(): Fix comparison warning
07158f4cf2a2 libfdt: overlay: Fix comparison warning
ce9e1f25a7de libfdt: fdt_resize(): Fix comparison warning
faa76fc10bc5 libfdt: fdt_splice_(): Fix comparison warning
54dca0985316 libfdt: fdt_get_string(): Fix comparison warnings
f8e11e61624e libfdt: fdt_grab_space_(): Fix comparison warning
0c43d4d7bf5a libfdt: fdt_mem_rsv(): Fix comparison warnings
442ea3dd1579 libfdt: fdt_offset_ptr(): Fix comparison warnings
ca19c3db2bf6 Makefile: Specify cflags for libyaml
7bb86f1c0956 libfdt: fix fdt_check_node_offset_ w/ VALID_INPUT
3d522abc7571 dtc: Include stdlib.h in util.h
808cdaaf524f dtc: Avoid UB when shifting
3e3138b4a956 libfdt: fix fdt_check_full buffer overrun

Signed-off-by: Rob Herring <robh@kernel.org>