OvmfPkg: Update LINUX_LOADER PcdImageProtectionPolicy to allow unaligned user images

[mikebeaton]

Required in some current distros, e.g. SliTaz https://slitaz.org/

$ objdump -p -h ~/Public/bootx64.efi 

/Users/mjsbeaton/Public/bootx64.efi:	file format coff-x86-64
Characteristics 0x206
	executable
	line numbers stripped
	debugging information removed

.
.
.
SectionAlignment        00000020
.
.
.
NumberOfRvaAndSizes     00000006

.
.
.

Sections:
Idx Name          Size     VMA              Type
  0 .setup        000035e0 0000000000000200 TEXT
  1 .reloc        00000020 00000000000037e0 DATA
  2 .text         003cf010 0000000000003800 TEXT
  3 .bss          00000000 00000000003d2810 BSS
$ 

bootx64.zip

[mikebeaton]

BTW this is not shim, nor even a standard build of the kernel. It is a lightweight distro which I was using to test HttpBoot, in fact. The bootx64.efi is the kernel, plus an extra loader which fetches its params from a text file. This image has section alignment 0x20, whereas the Pcd enforces (EFI_PAGE_SIZE=) 0x1000 for all images, by default. In OpenDuet and OpenCore native loader, we already have the Pcd changed, to not enforce that for user images (comments suggest this is to allow legacy Apple images) - so this distro I believe would already load via Duet; but it won't currently load in AUDK OVMF, even with LINUX_LOADER defined - hence this requested/suggested change.