arm64: Disable fine grained traps on boot

arm64: Disable fine grained traps on boot

The arm64 FEAT_FGT extension introduces a set of traps to EL2 for accesses
to small sets of registers and instructions from EL1 and EL0.  Currently
Linux makes no use of this feature, ensure that it is not active at boot by
disabling the traps during EL2 setup.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210401180942.35815-3-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>