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/configs/j721s2_evm_r5_defconfig b/configs/j721s2_evm_r5_defconfig
index 996efd4..4147b4e 100644
--- a/configs/j721s2_evm_r5_defconfig
+++ b/configs/j721s2_evm_r5_defconfig
@@ -138,6 +138,8 @@
 CONFIG_SPI=y
 CONFIG_DM_SPI=y
 CONFIG_CADENCE_QSPI=y
+CONFIG_HAS_CQSPI_REF_CLK=y
+CONFIG_CQSPI_REF_CLK=133333333
 CONFIG_SYSRESET=y
 CONFIG_SPL_SYSRESET=y
 CONFIG_SYSRESET_TI_SCI=y