package/rcw-smarc-sal28: don't override dependencies

Don't override RCW_SMARC_SAL28_DEPENDENCIES in a conditional

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit 7d653a7abd7f5e2fccb73343cb3f50ad0858bd0d)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/rcw-smarc-sal28/rcw-smarc-sal28.mk

@@ -14,7 +14,7 @@ RCW_SMARC_SAL28_INSTALL_IMAGES = YES
 RCW_SMARC_SAL28_BOOT_VARIANT = $(call qstrip,$(BR2_PACKAGE_RCW_SMARC_SAL28_BOOT_VARIANT))
 
 ifeq ($(BR2_PACKAGE_RCW_SMARC_SAL28_BUILD_UPDATE_SCRIPT),y)
-RCW_SMARC_SAL28_DEPENDENCIES = host-uboot-tools
+RCW_SMARC_SAL28_DEPENDENCIES += host-uboot-tools
 define RCW_SMARC_SAL28_UPDATE_SCRIPT_BUILD_CMDS
 	MKIMAGE=$(HOST_DIR)/bin/mkimage $(MAKE) -C $(@D)/contrib all
 endef