MdeModulePkg/SetupBrowserDxe: Do not reconnect driver with form-update

MdeModulePkg/SetupBrowserDxe: Do not reconnect driver with form-update

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2701

Recording to the spec, the reconnect is activated upon exiting of the
formset or the browser. Exiting is by user but form-browser internal
logic. That means the reconnection is only happened when user press
ESC or _EXIT action to exit form.
Driver callback may update HII form dynamically so form-browser needs
to refresh its internal data. It's not exiting formset for user
exactly and they didn't know what happened. So use a flag to record
that and do not reconnect driver if updated by callback.

Signed-off-by: Walon Li <walon.li@hpe.com>
Reviewed-by: Dandan Bi <dandan.bi@intel.com>