firmware: psci: introduce SPL_ARM_PSCI_FW

Introduce a new macro SPL_ARM_PSCI_FW

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Stefano Babic <sbabic@denx.de>
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 6cb8358..6c3e129 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -1,4 +1,4 @@
 obj-$(CONFIG_FIRMWARE)		+= firmware-uclass.o
-obj-$(CONFIG_ARM_PSCI_FW)	+= psci.o
+obj-$(CONFIG_$(SPL_)ARM_PSCI_FW)	+= psci.o
 obj-$(CONFIG_TI_SCI_PROTOCOL)	+= ti_sci.o
 obj-$(CONFIG_SANDBOX)		+= firmware-sandbox.o