Convert CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
   CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS

And we remove the entries from the README for a number of already
converted items.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/ls2088ardb_qspi_SECURE_BOOT_defconfig b/configs/ls2088ardb_qspi_SECURE_BOOT_defconfig
index 1972fc9..008ee1f 100644
--- a/configs/ls2088ardb_qspi_SECURE_BOOT_defconfig
+++ b/configs/ls2088ardb_qspi_SECURE_BOOT_defconfig
@@ -54,6 +54,7 @@
 CONFIG_SATA_CEVA=y
 CONFIG_DDR_CLK_FREQ=133333333
 CONFIG_DIMM_SLOTS_PER_CTLR=2
+CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS=2
 CONFIG_DDR_ECC=y
 CONFIG_ECC_INIT_VIA_DDRCONTROLLER=y
 CONFIG_SYS_FSL_DDR_INTLV_256B=y