Enable PM and PM_GENERIC_DOMAINS for SoCs with PM Domains

Hi Simon, Magnus,

All supported Renesas ARM SoCs (except for Emma Mobile EV2) have clock domains. Some SoCs also have power domains. To ensure proper operation of on-SoC modules, module clocks must be ungated, and power domains must be powered up when needed.

Currently the user can choose to build a kernel with power management enabled or disabled:
- If CONFIG_PM=y, power domains and/or module clocks are handled dynamically by Runtime PM and the generic power domain.
- If CONFIG_PM=n, power domains are assumed to be powered up by reset state or by the boot loader, and module clocks are handled by the legacy clock domain on driver (un)bind.
The latter is implemented using a platform bus notifier, which applies not only to all on-SoC devices, but to all platform devices present in the system.

To remove the dependency on implicit assumptions, and to get rid of the peculiarities of the legacy clock domain, enable CONFIG_PM and CONFIG_PM_GENERIC_DOMAINS unconditionally, for all Renesas ARM SoCs with clock and/or power domains.

Patches:
- Patches 1 and 2 enable PM and PM_GENERIC_DOMAINS,
- Patch 3 removes the now unused legacy clock domain code for Renesas ARM SoCs,
- Patch 4 relieves you from maintaining drivers/sh/, which is no longer used on Renesas ARM SoCs, and returns it to the SuperH people.

Notes:
- This does cause an increase in kernel size. Given bloat-o-meter reports a modest increase of 26 KiB for an RZ/A1H kernel, this should not be a problem, even when used on RZ/A1H with XIP and internal RAM only.
- Patch 3 does break booting R-Car Gen2 boards using pre-v4.3 DTSes that don't have power-domains properties,
- Patch 3 may unbreak SuperH-based ARCH_SHMOBILE platforms, which were probably broken since v4.4 by commit 0ba58de231066e47 ("drivers: sh:
Get rid of CONFIG_ARCH_SHMOBILE_MULTI"),
- Currently CONFIG_PM=n doesn't work anyway on r8a7795 as "drivers:
sh: Handle PM_GENERIC_DOMAINS_OF=n with new r8a7795 CPG/MSSR driver" isn't upstream.

For your convenience, I've also pushed this series to
git://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git#topic/mandatory-pm-v1

Thanks for your comments!

Geert Uytterhoeven (4):
ARM: shmobile: Enable PM and PM_GENERIC_DOMAINS for SoCs with PM
Domains
arm64: renesas: Enable PM and PM_GENERIC_DOMAINS for SoCs with PM
Domains

drivers: sh: Stop using the legacy clock domain on ARM
MAINTAINERS: Drop drivers/sh/ for Renesas ARM

 MAINTAINERS                    |  1 -
 arch/arm/mach-shmobile/Kconfig | 13 ++++++++-----
 arch/arm64/Kconfig.platforms   |  3 ++-
 drivers/Makefile               |  1 -
 drivers/sh/pm_runtime.c        |  9 ---------
 5 files changed, 10 insertions(+), 17 deletions(-)