Blackfin: use common LDSCRIPT logic

Now that common code is a bit smarter when it comes to default LDSCRIPT
values, rename the default Blackfin file and drop the Blackfin-specific
config.mk logic.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/config.mk

@@ -76,10 +76,6 @@ LDR_FLAGS += $(LDR_FLAGS-y)
 # Set some default LDR flags based on boot mode.
 LDR_FLAGS += $(LDR_FLAGS-$(CONFIG_BFIN_BOOT_MODE))
 
-ifeq ($(wildcard $(TOPDIR)/board/$(BOARD)/u-boot.lds*),)
-LDSCRIPT = $(obj)arch/$(ARCH)/lib/u-boot.lds.S
-endif
-
 ifneq ($(CONFIG_SYS_TEXT_BASE),)
 $(error do not set CONFIG_SYS_TEXT_BASE for Blackfin boards)
 endif