ubifs: Fix wrong dirty space budget for dirty inode

ubifs: Fix wrong dirty space budget for dirty inode

[ Upstream commit 8bd003aca5aa2b1c4ffad18e4986f6cc490e64e5 ]

Each dirty inode should reserve 'c->bi.inode_budget' bytes in space
budget calculation. Currently, space budget for dirty inode reports
more space than what UBIFS actually needs to write.

Fixes: 974763da840dbf ("UBIFS: add new flash file system")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Sasha Levin <sashal@kernel.org>