clk: tegra: Drop !provider check in tegra210_clk_emc_set_rate()

The provider variable is already dereferenced earlier in this function.
Drop the check for NULL as it is impossible.

Found with smatch

drivers/clk/tegra/clk-tegra210-emc.c:131 tegra210_clk_emc_set_rate() warn: variable dereferenced before check 'provider' (see line 124)

Cc: Joseph Lo <josephl@nvidia.com>
Cc: Thierry Reding <treding@nvidia.com>
Fixes: 0ac65fc946d3 ("clk: tegra: Implement Tegra210 EMC clock")
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/20200922191641.2305144-1-sboyd@kernel.org
Acked-by: Thierry Reding <treding@nvidia.com>

clk: tegra: Fix missing prototype for tegra210_clk_register_emc()

Include the Tegra driver's clk.h to pull in the prototype definition for
this function so that compilers don't warn about it being missing.

Fixes: 0ac65fc946d3 ("clk: tegra: Implement Tegra210 EMC clock")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

clk: tegra: Implement Tegra210 EMC clock

The EMC clock needs to carefully coordinate with the EMC controller
programming to make sure external memory can be properly clocked. Do so
by hooking up the EMC clock with an EMC provider that will specify which
rates are supported by the EMC and provide a callback to use for setting
the clock rate at the EMC.

Based on work by Peter De Schrijver <pdeschrijver@nvidia.com>.

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