Documentation: power: Use kcalloc() instead of kzalloc()

As noted in the "Deprecated Interfaces, Language Features, Attributes,
and Conventions" documentation [1], size calculations (especially
multiplication) should not be performed in memory allocator (or similar)
function arguments due to the risk of them overflowing. This could lead
to values wrapping around and a smaller allocation being made than the
caller was expecting. Using those allocations could lead to linear
overflows of heap memory and other misbehaviors.

So, in the example code use the purpose specific kcalloc() function
instead of the argument size * count in the kzalloc() function.

At the same time, modify the translations accordingly.

Signed-off-by: Erick Archer <erick.archer@gmx.com>
Reviewed-by: Hu Haowen <2023002089@link.tyut.edu.cn>
Reviewed-by: Yanteng Si <siyanteng@loongson.cn>
Reviewed-by: Hu Haowen <2023002089@link.tyut.edu.cn>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Documentation: power: Update outdated contents in opp.rst

Three problems have been revised:
1. CONFIG_PM_OPP no longer depends on CONFIG_PM.
2. opp_find_freq_{ceil, floor} is renamed as dev_pm_opp_find_freq_{ceil,
floor}.
3. Make it clear that the 'opp' struct is actually dev_pm_opp.

Signed-off-by: Tang Yizhou <tangyizhou@huawei.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

PM: Wrap documentation to fit in 80 columns

Wrap to 80 columns. No textual change except to correct some "it's" that
should be "its".

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

PM / OPP: Correct Documentation about library location

OPP library is now located in drivers/opp/ directory.

Signed-off-by: Yue Hu <huyue2@yulong.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

docs: power: convert docs to ReST and rename to *.rst

Convert the PM documents to ReST, in order to allow them to
build with Sphinx.

The conversion is actually:
- add blank lines and indentation in order to identify paragraphs;
- fix tables markups;
- add some lists markups;
- mark literal blocks;
- adjust title markups.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>