OvmfPkg: update -D E1000_ENABLE from Intel PROEFI v.07 to BootUtil v.22

OvmfPkg: update -D E1000_ENABLE from Intel PROEFI v.07 to BootUtil v.22

Jiaxin reports that the OvmfPkg/README instructions for downloading the
Intel PROEFI drivers, and the filenames in OvmfPkg/OvmfPkg*.fdf for
incorporating the same in the OVMF binaries, are no longer up to date; the
download link has stopped working.

Additionally, the IA32 driver binary is no more distributed by Intel.

Update OvmfPkg/README with new download instructions, and adapt the OVMF
FDF files.

With this driver in use for QEMU's e1000 NIC, the DH shell command prints,
as Controller Name, "Intel(R) PRO/1000 MT Network Connection". I
successfully tested DHCP and ping from the UEFI shell.

Cc: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Reported-by: Jiaxin Wu <jiaxin.wu@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=613
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Wu Jiaxin <jiaxin.wu@intel.com>
Reviewed-by: Wu Jiaxin <jiaxin.wu@intel.com>
Acked-by: Jordan Justen <jordan.l.justen@intel.com>