ext4: remove unnecessary e4b->bd_buddy_page check in ext4_mb_load_buddy_gfp

e4b->bd_buddy_page is only set if we initialize ext4_buddy successfully. So
e4b->bd_buddy_page is always NULL in error handle branch. Just remove the
dead check.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20230303172120.3800725-11-shikemeng@huaweicloud.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>