xlat v2: Remove IMAGE_EL define

xlat v2: Remove IMAGE_EL define

The Exception Level is now detected at runtime. This means that it is not
needed to hardcode the EL used by each image.

This doesn't result in a substantial increase of the image size because
the initialization functions that aren't used are garbage-collected by
the linker.

In AArch32 the current EL has been changed from EL3 to EL1 because the
the AArch32 PL1&0 translation regime behaves more like the AArch64 EL1&0
translation regime than the EL3 one.

Change-Id: I941404299ebe7666ca17619207c923b49a55cb73
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>