boot/arm-trusted-firmware: allow enabling without uboot or edk2

It should be possible to compile ARM_TRUSTED_FIRMWARE without u-boot or EDK2.
For example, one might want to produce "bl31.bin" for use as an init stub for
the Raspberry Pi 4.

Signed-off-by: Christian Stewart <christian@paral.in>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

boot/arm-trusted-firmware/Config.in

@@ -1,7 +1,6 @@
 config BR2_TARGET_ARM_TRUSTED_FIRMWARE
 	bool "ARM Trusted Firmware (ATF)"
-	depends on (BR2_ARM_CPU_ARMV8A || BR2_ARM_CPU_ARMV7A) && \
-		   (BR2_TARGET_UBOOT || BR2_TARGET_EDK2)
+	depends on (BR2_ARM_CPU_ARMV8A || BR2_ARM_CPU_ARMV7A)
 	help
 	  Enable this option if you want to build the ATF for your ARM
 	  based embedded device.