Makefile: Make flash.bin target available for all platforms

There is no reason for restricting the use of the flash.bin target
to the i.MX8 platform. Others can benefit from this as well.

Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
diff --git a/Makefile b/Makefile
index 3866cc6..24926bf 100644
--- a/Makefile
+++ b/Makefile
@@ -1525,7 +1525,7 @@
 SPL: spl/u-boot-spl.bin FORCE
 	$(Q)$(MAKE) $(build)=arch/arm/mach-imx $@
 
-ifeq ($(CONFIG_ARCH_IMX8M)$(CONFIG_ARCH_IMX8), y)
+#ifeq ($(CONFIG_ARCH_IMX8M)$(CONFIG_ARCH_IMX8), y)
 ifeq ($(CONFIG_SPL_LOAD_IMX_CONTAINER), y)
 u-boot.cnt: u-boot.bin FORCE
 	$(Q)$(MAKE) $(build)=arch/arm/mach-imx $@
@@ -1541,7 +1541,7 @@
 	$(Q)$(MAKE) $(build)=arch/arm/mach-imx $@
 endif
 endif
-endif
+#endif
 
 u-boot.uim: u-boot.bin FORCE
 	$(Q)$(MAKE) $(build)=arch/arm/mach-imx $@