f2fs_utils: Add support for blocksize arguement

Adds -b option which is passed through to mkfs, allowing formatting for
different f2fs blocksizes.

Change-Id: I000cd5d1ae58786e562cc8226cacc1ac7ab5bc55
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Bug: 279820706
Test: Boot 16K device
1 file changed