ext4: remove redundant function ext4_has_metadata_csum

ext4: remove redundant function ext4_has_metadata_csum

Since commit f2b4fa19647e ("ext4: switch to using the crc32c library"),
ext4_has_metadata_csum() is just an alias for
ext4_has_feature_metadata_csum().  ext4_has_feature_metadata_csum() is
generated by EXT4_FEATURE_RO_COMPAT_FUNCS and uses the regular naming
convention for checking a single ext4 feature.  Therefore, remove
ext4_has_metadata_csum() and update all its callers to use
ext4_has_feature_metadata_csum() directly.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://patch.msgid.link/20250207031335.42637-1-ebiggers@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>