shmem: make shmem_inode_acct_block() return error

Make shmem_inode_acct_block() return proper error code instead of bool.
This will be useful later when we introduce quota support.

There should be no functional change.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-Id: <20230725144510.253763-2-cem@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>