OvmfPkg: QemuFlashFvbServicesRuntimeDxe: clean up includes and libraries

OvmfPkg: QemuFlashFvbServicesRuntimeDxe: clean up includes and libraries

Before introducing the SMM driver interface, clean up #include directives
and [LibraryClasses] by:
- removing what's not directly used (HobLib and UefiLib),
- adding what's used but not spelled out (DevicePathLib),
- sorting the result.

This helps with seeing each source file's dependencies and with
determining the library classes for the SMM driver.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18672 6f19259b-4bc3-4df7-8a09-765794883524