MdePkg/Uefi ARM: only support native ARM/Thumb images
MdePkg/Uefi ARM: only support native ARM/Thumb images

The ARM calling convention is fundamentally incompatible with EBC,
and having a cross compatible machine type identical to the native
type does not make a lot of sense either. So restrict the compatible
machine type for ARM to EFI_IMAGE_MACHINE_ARMTHUMB_MIXED, and remove
the cross compatible.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <66d3c5fdaeea7ff1f996ad04f2c45e08ab38e2f5@linaro.org>
Reviewed-by: Leif Lindholm <a613079f0455438b29e28a9c5b9eb3779a81a33a@linaro.org>
Reviewed-by: Liming Gao <6480311aeeb4b006862f6d13ebabddc03f51e507@intel.com>

MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2