devicetree: Add method to delete property by name

Will be used on Cavium SoC to delete devicetree entries that aren't
available with the board/configuration.

Change-Id: I7c58a2411206bca62d0e96fa627530e937383ac9
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/26693
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
2 files changed