ext4: Enable support for ext4 multi-fsblock atomic write using bigalloc

Last couple of patches added the needed support for multi-fsblock atomic
writes using bigalloc. This patch ensures that filesystem advertizes the
needed atomic write unit min and max values for enabling multi-fsblock
atomic write support with bigalloc.

Acked-by: Darrick J. Wong <djwong@kernel.org>
Co-developed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://patch.msgid.link/5e45d7ed24499024b9079436ba6698dae5298e29.1747337952.git.ritesh.list@gmail.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>