plat: remove redundant =1 from -D option

As GCC manual says, -D option defines a macro as 1, if =<value> is omitted.

  -D <name>
      Predefine <name> as a macro, with definition 1.

The same applied with Clang, too.

In the context of -D option, =1 is always redundant.

Change-Id: I487489a1ea3eb51e734741619c1e65dab1420bc4
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/plat/socionext/uniphier/platform.mk b/plat/socionext/uniphier/platform.mk
index cbe75d6..8819545 100644
--- a/plat/socionext/uniphier/platform.mk
+++ b/plat/socionext/uniphier/platform.mk
@@ -17,8 +17,8 @@
 ALLOW_RO_XLAT_TABLES			:= 1
 
 ifeq ($(ALLOW_RO_XLAT_TABLES),1)
-BL31_CPPFLAGS += -DPLAT_RO_XLAT_TABLES=1
-BL32_CPPFLAGS += -DPLAT_RO_XLAT_TABLES=1
+BL31_CPPFLAGS += -DPLAT_RO_XLAT_TABLES
+BL32_CPPFLAGS += -DPLAT_RO_XLAT_TABLES
 endif
 
 # Cortex-A53 revision r0p4-51rel0