ext4: remove ext4_block_group and ext4_block_group_offset declaration

For ext4_block_group and ext4_block_group_offset, there are only
declaration without definition. Just remove them.
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20230603150327.3596033-7-shikemeng@huaweicloud.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/ext4.h

@@ -2632,10 +2632,6 @@ extern void ext4_get_group_no_and_offset(struct super_block *sb,
 extern ext4_group_t ext4_get_group_number(struct super_block *sb,
 					  ext4_fsblk_t block);
 
-extern unsigned int ext4_block_group(struct super_block *sb,
-			ext4_fsblk_t blocknr);
-extern ext4_grpblk_t ext4_block_group_offset(struct super_block *sb,
-			ext4_fsblk_t blocknr);
 extern int ext4_bg_has_super(struct super_block *sb, ext4_group_t group);
 extern unsigned long ext4_bg_num_gdb(struct super_block *sb,
 			ext4_group_t group);