nxp: Migrate CONFIG_DDR_CLK_FREQ to Kconfig

As this symbol can either be a fixed value or the function
get_board_ddr_clk, migration is tricky.  Introduce a choice of DYNAMIC
or STATIC_DDR_CLK_FREQ.  If DYNAMIC, we continue to use the board
defined get_board_ddr_clk function.  If STATIC, set CONFIG_DDR_CLK_FREQ
to that value and now include/clock_legacy.h contains the function
prototype or defines get_board_ddr_clk() to that static value.  Update
callers to test for DYNAMIC or STATIC.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/ddr/Kconfig b/drivers/ddr/Kconfig
index 0b767ac..eec9d48 100644
--- a/drivers/ddr/Kconfig
+++ b/drivers/ddr/Kconfig
@@ -1,3 +1,29 @@
+choice
+	prompt "Method to determine DDR clock frequency"
+	default STATIC_DDR_CLK_FREQ
+	depends on ARCH_P1010 || ARCH_P1020 || ARCH_P2020 || ARCH_T1024 \
+		|| ARCH_T1042 || ARCH_T2080 || ARCH_T4240 || ARCH_LS1021A \
+		|| FSL_LSCH2 || FSL_LSCH3 || TARGET_KMCENT2
+	help
+	  The DDR clock frequency can either be defined statically now at
+	  build time, or can be determined at run-time via the
+	  get_board_ddr_clk function.
+
+config DYNAMIC_DDR_CLK_FREQ
+	bool "Run-time DDR clock frequency"
+
+config STATIC_DDR_CLK_FREQ
+	bool "Build-time static DDR clock frequency"
+
+endchoice
+
+config DDR_CLK_FREQ
+	int "DDR clock frequency in Hz"
+	depends on STATIC_DDR_CLK_FREQ
+	default 100000000
+	help
+	  The DDR clock frequency, specified in Hz.
+
 config DDR_SPD
 	bool "JEDEC Serial Presence Detect (SPD) support"
 	help