sel-cache: Use sel cache for getSELEntry()

Use the cached SEL info in getSELEntry().
There will be future commits to use the cached SEL for other handlers.

Tested: Verify ipmi sel list and sel get works OK.
        Verify the sel list time is reduced, e.g. on g220a with 100 SEL
        entries, the list time is reduced from about 6s to 2s.

Signed-off-by: Lei YU <yulei.sh@bytedance.com>
Change-Id: I908b21baf47220c8556ad92446a9cb04879090d4
1 file changed