arm64: sysreg: Replace HFGxTR_EL2 with HFG{R,W}TR_EL2

arm64: sysreg: Replace HFGxTR_EL2 with HFG{R,W}TR_EL2

Treating HFGRTR_EL2 and HFGWTR_EL2 identically was a mistake.
It makes things hard to reason about, has the potential to
introduce bugs by giving a meaning to bits that are really reserved,
and is in general a bad description of the architecture.

Given that #defines are cheap, let's describe both registers as
intended by the architecture, and repaint all the existing uses.

Yes, this is painful.

The registers themselves are generated from the JSON file in
an automated way.

Signed-off-by: Marc Zyngier <maz@kernel.org>