iommu/omap: streamline enable/disable through runtime pm callbacks

iommu/omap: streamline enable/disable through runtime pm callbacks

The OMAP IOMMU devices are typically present within the respective
client processor subsystem and have their own dedicated hard-reset
line. Enabling an IOMMU requires the reset line to be deasserted
and the clocks to be enabled before programming the necessary IOMMU
registers. The IOMMU disable sequence follow the reverse order of
enabling. The OMAP IOMMU driver programs the reset lines through
pdata ops to invoke the omap_device_assert/deassert_hardreset API.
The clocks are managed through the pm_runtime framework, and the
callbacks associated with the device's pm_domain, implemented in
the omap_device layer.

Streamline the enable and disable sequences in the OMAP IOMMU
driver by implementing all the above operations within the
runtime pm callbacks. All the OMAP devices have device pm_domain
callbacks plugged in the omap_device layer for automatic runtime
management of the clocks. Invoking the reset management functions
within the runtime pm callbacks in OMAP IOMMU driver therefore
requires that the default device's pm domain callbacks in the
omap_device layer be reset, as the ordering sequence for managing
the reset lines and clocks from the pm_domain callbacks don't gel
well with the implementation in the IOMMU driver callbacks. The
omap_device_enable/omap_device_idle functions are invoked through
the newly added pdata ops.

Consolidating all the device management sequences within the
runtime pm callbacks allows the driver to easily support both
system suspend/resume and runtime suspend/resume using common
code.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>