staging: erofs: fix 1 warning and 9 checks

This patch does not change the logic, it only
corrects the formatting and checkpatch checks by
braces {} should be used on all arms of this statement,
unbalanced braces around else statement and warning by
braces {} are not necessary for any arm of this statement.

The patch fixes 9 checks of type:
"Check: braces {} should be used on all arms of this statement";
"Check: Unbalanced braces around else statement";

and 1 warning of type:
"WARNING: braces {} are not necessary for any arm of this statement".

Signed-off-by: Pavel Zemlyanoy <zemlyanoy@ispras.ru>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Reviewed-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>