Enable all supported metadata sizes in LUKS2 validation code.

LUKS2 specification allows various size of LUKS2 metadata.
The single metadata instance is composed of LUKS2 binary header
(4096 bytes) and immediately following json area. The resulting
assembled metadata size have to be one of following values,
all in KiB:

16, 32, 64, 128, 256, 512, 1024, 2048 or 4096