configs: Migrate CONFIG_SYS_LDSCRIPT to Kconfig

In order to migrate this symbol to Kconfig introduce a new symbol to
guard it, CONFIG_SYS_CUSTOM_LDSCRIPT.  When that is set we can then
provide the exact final location o the script.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/zynq_cse_qspi_defconfig b/configs/zynq_cse_qspi_defconfig
index 2aaa814..8f9ba07 100644
--- a/configs/zynq_cse_qspi_defconfig
+++ b/configs/zynq_cse_qspi_defconfig
@@ -13,6 +13,8 @@
 # CONFIG_ZYNQ_DDRC_INIT is not set
 # CONFIG_CMD_ZYNQ is not set
 CONFIG_DEBUG_UART=y
+CONFIG_SYS_CUSTOM_LDSCRIPT=y
+CONFIG_SYS_LDSCRIPT="arch/arm/mach-zynq/u-boot.lds"
 # CONFIG_ARCH_FIXUP_FDT_MEMORY is not set
 # CONFIG_BOARD_LATE_INIT is not set
 # CONFIG_DISPLAY_CPUINFO is not set