openrisc: Use asm-generic's version of fix_to_virt() & virt_to_fix()

Openrisc's implementation of fix_to_virt() & virt_to_fix() share same
functionality with ones of asm generic.

Plus, generic version of fix_to_virt() can trap invalid index at compile
time.

Thus, Replace the arch-specific implementations with asm generic's ones.

Signed-off-by: Dawei Li <set_pte_at@outlook.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

openrisc: explicitly include linux/bug.h in asm/fixmap.h

openrisc's asm/fixmap.h uses the BUG() and BUG_ON() macros but relies on
implict inclusion of linux/bug.h which means that changes in other
headers could break the build. Thus, add an explicit include.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Stafford Horne <shorne@gmail.com>

OpenRISC: Memory management

Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>