clk: imx: add configuration option for mmio clks

The patch introduces CONFIG_MXC_CLK option for legacy MMIO clocks,
this is required to compile legacy MMIO clock conditionally when adding
SCU based clocks for MX8 platforms later.

Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Michael Turquette <mturquette@baylibre.com>
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/Kconfig

@@ -287,6 +287,7 @@ source "drivers/clk/actions/Kconfig"
 source "drivers/clk/bcm/Kconfig"
 source "drivers/clk/hisilicon/Kconfig"
 source "drivers/clk/imgtec/Kconfig"
+source "drivers/clk/imx/Kconfig"
 source "drivers/clk/ingenic/Kconfig"
 source "drivers/clk/keystone/Kconfig"
 source "drivers/clk/mediatek/Kconfig"

drivers/clk/Makefile

@@ -71,7 +71,7 @@ obj-$(CONFIG_ARCH_DAVINCI)		+= davinci/
 obj-$(CONFIG_H8300)			+= h8300/
 obj-$(CONFIG_ARCH_HISI)			+= hisilicon/
 obj-y					+= imgtec/
-obj-$(CONFIG_ARCH_MXC)			+= imx/
+obj-y					+= imx/
 obj-y					+= ingenic/
 obj-$(CONFIG_ARCH_K3)			+= keystone/
 obj-$(CONFIG_ARCH_KEYSTONE)		+= keystone/

drivers/clk/imx/Kconfig

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
+# common clock support for NXP i.MX SoC family.
+config MXC_CLK
+	bool
+	def_bool ARCH_MXC

drivers/clk/imx/Makefile

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
-obj-y += \
+obj-$(CONFIG_MXC_CLK) += \
 	clk.o \
 	clk-busy.o \
 	clk-cpu.o \