Revert "fs: ext4: check the minimal partition size to mount"

This check breaks small partitions (under 1024 blocks) because part_length
is in units of part.blksz and not bytes. Given the purpose of this
function, we really want to make sure the partition is SUPERBLOCK_START +
SUPERBLOCK_SIZE (2048) bytes so we can call ext4_read_superblock without
error.

The obvious solution is to convert callers from things like

	ext4fs_mount(part_info.size)

to

	ext4fs_mount(part_info.size * part_info.blksz);

However, I'm not really a fan of the bloat that would cause, especially
since the error is now suppressed. I think the best course of action here
is to just revert the patch.

This reverts commit 9905cae6.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>