busfreq-imx: only use existing global variables

The struct arm_reg and soc_reg are declared in by a extern statement
in include/linux/busfreq-imx.h. However they are only declared when
imx6-cpufreq.c is compiled and linked.

Qualify the use of arm_reg and soc_reg with the relevant config option
and change KConfig to switch that option on for the SoCs which use
it.

This fixes the following build issue when building for i.MX 7 with
option ARM_IMX6Q_CPUFREQ not set:

arch/arm/mach-imx/built-in.o: In function `imx6ull_lower_cpu_rate':
platform-imx-dma.c:(.text+0x5514): undefined reference to `arm_reg'
platform-imx-dma.c:(.text+0x551c): undefined reference to `arm_reg'
platform-imx-dma.c:(.text+0x553c): undefined reference to `soc_reg'
platform-imx-dma.c:(.text+0x5544): undefined reference to `soc_reg'
platform-imx-dma.c:(.text+0x5598): undefined reference to `arm_reg'
platform-imx-dma.c:(.text+0x55a0): undefined reference to `arm_reg'
platform-imx-dma.c:(.text+0x55ac): undefined reference to `soc_reg'
platform-imx-dma.c:(.text+0x55b4): undefined reference to `soc_reg'
platform-imx-dma.c:(.text+0x55c8): undefined reference to `soc_reg'
platform-imx-dma.c:(.text+0x55d0): undefined reference to `soc_reg'
platform-imx-dma.c:(.text+0x55f0): undefined reference to `arm_reg'
platform-imx-dma.c:(.text+0x55f8): undefined reference to `arm_reg'

Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
Acked-by: Dominik Sliwa <dominik.sliwa@toradex.com>
(cherry picked from commit 3f68dc7c600c0354f5df7f06b931661319addafb)
(cherry picked from commit e9289b70128d018c12adb591d62724e09cc5b1a6)

Conflicts:
	arch/arm/mach-imx/Kconfig
Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>

0 files changed, 0 insertions, 0 deletions