ext4: Make ext4_meta_trans_blocks() non-static for later use

ext4: Make ext4_meta_trans_blocks() non-static for later use

Let's make ext4_meta_trans_blocks() non-static for use in later
functions during ->end_io conversion for atomic writes.
We will need this function to estimate journal credits for a special
case. Instead of adding another wrapper around it, let's make this
non-static.

Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://patch.msgid.link/23ce80d4286f792831ce99d13558182ee228fedb.1747337952.git.ritesh.list@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>