PM / devfreq: tegra: Rename tegra-devfreq.c to tegra30-devfreq.c

In order to reflect that driver serves NVIDIA Tegra30 and later SoC
generations, let's rename the driver's source file to "tegra30-devfreq.c".
This will make driver files to look more consistent after addition of a
driver for Tegra20.

Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
index 32b8d4d..47e5aee 100644
--- a/drivers/devfreq/Makefile
+++ b/drivers/devfreq/Makefile
@@ -10,7 +10,7 @@
 # DEVFREQ Drivers
 obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ)	+= exynos-bus.o
 obj-$(CONFIG_ARM_RK3399_DMC_DEVFREQ)	+= rk3399_dmc.o
-obj-$(CONFIG_ARM_TEGRA_DEVFREQ)		+= tegra-devfreq.o
+obj-$(CONFIG_ARM_TEGRA_DEVFREQ)		+= tegra30-devfreq.o
 
 # DEVFREQ Event Drivers
 obj-$(CONFIG_PM_DEVFREQ_EVENT)		+= event/