This adds the following commits from upstream:

b1a6003 tests: Add a test for overlays syntactic sugar
737b2df overlay: Add syntactic sugar version of overlays
497432f checks: Use proper format modifier for size_t
22a65c5 dtc: Bump version to v1.4.5
c575d80 Add fdtoverlay to .gitignore
b6a6f94 fdtoverlay: Sanity check blob size
8c1eb15 pylibfdt: Use Python2 explicitly
ee3d26f checks: add interrupts property check
c1e7738 checks: add gpio binding properties check
b3bbac0 checks: add phandle with arg property checks

[ sync with Linux commit: 4201d057ea91c3d6efd2db65219bc91fae413bc2 ]

Signed-off-by: Masahiro Yamada