binman: u-boot-dtb vs. filename

[Jan Kiszka]

Hi,

I stumbled over README.entries claiming

Entry: u-boot-dtb: U-Boot device tree
-------------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot.dtb (default 'u-boot.dtb')


However,

	u-boot-dtb {
		filename = "foo.dtb"
	}

only pulls u-boot.dtb. Tried to fix that but I failed to understand the
binman logic. Maybe the documentation (also that of
u-boot-dtb-with-ucode) was just not supposed to refer to filename.

Using 'blob' now, like other boards.

Jan