memory: tegra124-emc: Make driver modular

Add modularization support to the Tegra124 EMC driver, which now can be
compiled as a loadable kernel module.

Note that EMC clock must be registered at clk-init time, otherwise PLLM
will be disabled as unused clock at boot time if EMC driver is compiled
as a module. Hence add a prepare/complete callbacks. similarly to what is
done for the Tegra20/30 EMC drivers.

Tested-by: Nicolas Chauvet <kwizart@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Link: https://lore.kernel.org/r/20201228154920.18846-2-digetx@gmail.com
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

clk: tegra: Rename Tegra124 EMC clock source file

This code is only used on Tegra124, so rename it accordingly to make it
more consistent with other file names.

While at it, also get rid of the TEGRA_CLK_EMC Kconfig symbol that's
really just an alias for TEGRA124_EMC.

Signed-off-by: Thierry Reding <treding@nvidia.com>

treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

clk: tegra: dfll: build clk-dfll.c for Tegra124 and Tegra210

Tegra210 has a DFLL as well and can share the majority of the code with
the Tegra124 implementation. So build the same code for both platforms.

Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: Joseph Lo <josephl@nvidia.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>

clk: tegra: Add BPMP clock driver

This driver uses the services provided by the BPMP firmware driver to
implement a clock driver based on the MRQ_CLK request. This part of the
BPMP ABI provides a means to enumerate and control clocks and should
allow the driver to work on any chip that supports this ABI.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

clk: tegra: EMC clock driver depends on EMC driver

The EMC clock driver uses symbols exported by the EMC driver, so it
needs the corresponding dependency to avoid build breakage.

Signed-off-by: Thierry Reding <treding@nvidia.com>