spi: cadence_qspi: Migrate CONFIG_CQSPI_REF_CLK to Kconfig

This is a little tricky since SoCFPGA has code to determine this as
runtime.  Introduce a guard variable for platforms to select if they
have a static value to use.  Then for ARCH_SOCFPGA, call
cm_get_qspi_controller_clk_hz() and otherwise continue the previous
behavior.

Cc: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 423a757..8dba95a 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -128,6 +128,14 @@
 	  used to access the SPI NOR flash on platforms embedding this
 	  Cadence IP core.
 
+config HAS_CQSPI_REF_CLK
+	bool "Cadence QSPI static reference clock"
+	depends on CADENCE_QSPI
+
+config CQSPI_REF_CLK
+	int "Cadence QSPI reference clock value in Hz"
+	depends on HAS_CQSPI_REF_CLK
+
 config CF_SPI
         bool "ColdFire SPI driver"
         help