arch,cpu: Rename arch/registers.hh to arch/vecregs.hh.

The only thing still in arch/registers.hh were related to vector
registers. To make it obvious that nothing else should be added, this
change renames the file so that it has the much less generic name
arch/vecregs.hh.

Change-Id: I729697dc576e1978047688d9700dc07ff9b17044
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/42686
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/dev/riscv/clint.hh

@@ -39,7 +39,6 @@
 #define __DEV_RISCV_CLINT_HH__
 
 #include "arch/riscv/interrupts.hh"
-#include "arch/riscv/registers.hh"
 #include "dev/intpin.hh"
 #include "dev/io_device.hh"
 #include "dev/mc146818.hh"

src/dev/riscv/plic.cc

@@ -40,7 +40,6 @@
 
 #include <algorithm>
 
-#include "arch/riscv/registers.hh"
 #include "cpu/base.hh"
 #include "debug/Plic.hh"
 #include "mem/packet.hh"