MINOR: ssl_ckch: Simplify I/O handler to commit changes on CA/CRL entry

MINOR: ssl_ckch: Simplify I/O handler to commit changes on CA/CRL entry

Simplify cli_io_handler_commit_cafile_crlfile() handler function by
retrieving old and new entries at the beginning. In addition the path is
also retrieved at this stage. This removes several switch statements.

Note that the ctx was already validated by the corresponding parsing
function. Thus there is no reason to test the pointers.

While it is not a bug, this patch may help to fix issue #1731.