Corrected the logic for calculating the expiration no of days

[shtripat]

Description

Earlier ILM rule's set value of expiration days was getting deducted from current time and so the final value of no of days to expiration was coming as a -ve value (as expiration day would be in future and deducting from current day would result into a -ve value). Reversed the order of arguments to subtract function and works as expected.

Now the corrected output of command mc ilm rule ls <minio-cluster-name>/<bucket-name> looks as below

┌────────────────────────────────────────────────────────────────────────────────┐
│ Expiration for latest version (Expiration)                                     │
├───────────────┬─────────┬────────┬──────┬────────────────┬─────────────────────┤
│ ID            │ STATUS  │ PREFIX │ TAGS │ DAYS TO EXPIRE │ EXPIRE DELETEMARKER │
├───────────────┼─────────┼────────┼──────┼────────────────┼─────────────────────┤
│ expire-bucket │ Enabled │ -      │ -    │             23 │ false               │
└───────────────┴─────────┴────────┴──────┴────────────────┴─────────────────────┘

Motivation and Context

fixes bug #4446

How to test this PR?

Follow the below steps to test the PR
Step-1: Create a bucket using minio console
Step-2: Set the ilm rule using below command

mc ilm import minio/102938-4-300 <<EOF
{
"Rules": [
{
"Expiration": {
"Date": "2023-02-16T00:00:00Z"
},
"ID": "expire-bucket",
"Status": "Enabled"
}
]
}
EOF

Step-3: Check the minio console to see if rule gets listed as enabled
Step-4: Verify the changes using mc command mc ilm rule ls myminio/102938-4-300. The output should be as below

┌────────────────────────────────────────────────────────────────────────────────┐
│ Expiration for latest version (Expiration)                                     │
├───────────────┬─────────┬────────┬──────┬────────────────┬─────────────────────┤
│ ID            │ STATUS  │ PREFIX │ TAGS │ DAYS TO EXPIRE │ EXPIRE DELETEMARKER │
├───────────────┼─────────┼────────┼──────┼────────────────┼─────────────────────┤
│ expire-bucket │ Enabled │ -      │ -    │             23 │ false               │
└───────────────┴─────────┴────────┴──────┴────────────────┴─────────────────────┘

``

## Types of changes
- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Optimization (provides speedup with no functional changes)
- [ ] Breaking change (fix or feature that would cause existing functionality to change)

## Checklist:
- [ ] Fixes a regression (If yes, please add `commit-id` or `PR #` here)
- [ ] Unit tests added/updated
- [ ] Internal documentation updated
- [ ] Create a documentation update request [here](https://github.com/minio/docs/issues/new?label=doc-change,title=Doc+Updated+Needed+For+PR+github.com%2fminio%2fmc%2fpull%2fNNNNN)

[klauspost]

LGTM