ext4: remove unneeded check of nr_to_submit

ext4: remove unneeded check of nr_to_submit

cppcheck reports
fs/ext4/page-io.c:516:51: style:
  Condition 'nr_to_submit' is always true [knownConditionTrueFalse]
 if (fscrypt_inode_uses_fs_layer_crypto(inode) && nr_to_submit) {
                                                  ^
This earlier check to bail, makes this check unncessary
	/* Nothing to submit? Just unlock the page... */
	if (!nr_to_submit)
		return 0;

Signed-off-by: Tom Rix <trix@redhat.com>
Fixes: dff4ac75eeee ("ext4: move keep_towrite handling to ext4_bio_write_page()")
Reviewed-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20230316204831.2472537-1-trix@redhat.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>