ext4: functions should not be declared extern

The function declarations in ext4.h are already marked extern, so it's
not necessary to do so in the .c files.

This quiets the sparse noise:

warning: function 'ext4_flush_completed_IO' with external linkage has definition
warning: function 'ext4_init_inode_table' with external linkage has definition
Signed-off-by: NH Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/fsync.c

@@ -75,7 +75,7 @@ static void dump_completed_IO(struct inode * inode)
  * to written.
  * The function return the number of pending IOs on success.
  */
-extern int ext4_flush_completed_IO(struct inode *inode)
+int ext4_flush_completed_IO(struct inode *inode)
 {
 	ext4_io_end_t *io;
 	struct ext4_inode_info *ei = EXT4_I(inode);

fs/ext4/ialloc.c

@@ -1100,7 +1100,7 @@ unsigned long ext4_count_dirs(struct super_block * sb)
  * inode allocation from the current group, so we take alloc_sem lock, to
  * block ext4_claim_inode until we are finished.
  */
-extern int ext4_init_inode_table(struct super_block *sb, ext4_group_t group,
+int ext4_init_inode_table(struct super_block *sb, ext4_group_t group,
 				 int barrier)
 {
 	struct ext4_group_info *grp = ext4_get_group_info(sb, group);