arch-arm: Replace direct use cpsr.el with currEL helper

The patch is replacing it in places where the current EL could be using
AArch32, hence leading to an incorrect ExceptionLevel.

Change-Id: I99b75af2668f2c38fd88bec62e985ab7dbea80dc
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/20251
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

style: [patch 1/22] use /r/3648/ to reorganize includes

arm: Fix secure state checking in various places

Faults that could potentially be routed to the hypervisor checked
whether or not they were in a secure state without checking if security
was enabled or not. This caused faults not to be routed correctly. This
patch causes secure state checking to first ask if security is enabled.

Change-Id: I179e9b181b27f552734c9bab2b18d05ac579a119

style: remove trailing whitespace

Result of running 'hg m5style --skip-all --fix-white -a'.

arm: Add support for ARMv8 (AArch64 & AArch32)

Note: AArch64 and AArch32 interworking is not supported. If you use an AArch64
kernel you are restricted to AArch64 user-mode binaries. This will be addressed
in a later patch.

Note: Virtualization is only supported in AArch32 mode. This will also be fixed
in a later patch.

Contributors:
Giacomo Gabrielli (TrustZone, LPAE, system-level AArch64, AArch64 NEON, validation)
Thomas Grocutt (AArch32 Virtualization, AArch64 FP, validation)
Mbou Eyole (AArch64 NEON, validation)
Ali Saidi (AArch64 Linux support, code integration, validation)
Edmund Grimley-Evans (AArch64 FP)
William Wang (AArch64 Linux support)
Rene De Jong (AArch64 Linux support, performance opt.)
Matt Horsnell (AArch64 MP, validation)
Matt Evans (device models, code integration, validation)
Chris Adeniyi-Jones (AArch64 syscall-emulation)
Prakash Ramrakhyani (validation)
Dam Sunwoo (validation)
Chander Sudanthi (validation)
Stephan Diestelhorst (validation)
Andreas Hansson (code integration, performance opt.)
Eric Van Hensbergen (performance opt.)
Gabe Black

ARM: Implement ARM CPU interrupts

ARM: Boilerplate full-system code.