boot/arm-trusted-firmware: remove extra ending parentheses

There are two extra ending parentheses to be removed.
They are present from the beggining of TF-A package. I suppose extra
ending parenthese does not bring any issue, but it seems relevant to
remove them.

Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

boot/arm-trusted-firmware/arm-trusted-firmware.mk

@@ -202,8 +202,8 @@ endef
 ifeq ($(BR2_TARGET_ARM_TRUSTED_FIRMWARE)$(BR_BUILDING),yy)
 
 ifeq ($(ARM_TRUSTED_FIRMWARE_VERSION),custom)
-ifeq ($(call qstrip,$(BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_TARBALL_LOCATION))),)
-$(error No tarball location specified. Please check BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_TARBALL_LOCATION))
+ifeq ($(call qstrip,$(BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_TARBALL_LOCATION)),)
+$(error No tarball location specified. Please check BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_TARBALL_LOCATION)
 endif
 endif