powerpc: mm: convert to GENERIC_IOREMAP

powerpc: mm: convert to GENERIC_IOREMAP

By taking GENERIC_IOREMAP method, the generic generic_ioremap_prot(),
generic_iounmap(), and their generic wrapper ioremap_prot(), ioremap()
and iounmap() are all visible and available to arch. Arch needs to
provide wrapper functions to override the generic versions if there's
arch specific handling in its ioremap_prot(), ioremap() or iounmap().
This change will simplify implementation by removing duplicated code
with generic_ioremap_prot() and generic_iounmap(), and has the equivalent
functioality as before.

Here, add wrapper functions ioremap_prot() and iounmap() for powerpc's
special operation when ioremap() and iounmap().

Link: https://lkml.kernel.org/r/20230706154520.11257-18-bhe@redhat.com
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>