boot/efi/x86: take care of PAE flags during MMU initialization

UEFI specification states that on IA-32 paging may or may not be
enabled during startup. If paging is enabled, PAE might be active.

During jump to kernel and early kernel initialiation we use paging
without PAE.

Therefore the following initialization sequence is introduced:
* disable paging
* disable PAE
* load page directory
* enable paging

Change-Id: Ife9a631b914dd5867f6673713e20e8abfce1ea44
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4919
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

boot/efi/x86: implement MMU initialization and jump to kernel

Change-Id: Ie42c69f3851acae3a8184aa97ab2dd01c9485f46
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4850
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>