OvmfPkg: Use NestedInterruptTplLib in nested interrupt handlers

OvmfPkg: Use NestedInterruptTplLib in nested interrupt handlers

Prevent stack underrun in the event of a timer interrupt storm in
LocalApicTimerDxe and 8254TimerDxe interrupt handlers by using the
helper functions provided by NestedInterruptTplLib.

This fixes the same problem as addressed in commit 239b50a86
("OvmfPkg: End timer interrupt later to avoid stack overflow under
load"), but does so without breaking nested timer interrupts.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2815
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=4162
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Acked-by: Laszlo Ersek <lersek@redhat.com>