kbuild: drop CONFIG_USE_PRIVATE_LIBGCC=path/to/libgcc syntax

Now CONFIG_USE_PRIVATE_LIBGCC is only used as a boolean macro.
Remove CONFIG_USE_PRIVATE_LIBGCC=path/to/libgcc syntax.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Tested-by: Simon Glass <sjg@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org>

Makefile

@@ -674,13 +674,9 @@ u-boot-main := $(libs-y)
 
 
 # Add GCC lib
-ifdef CONFIG_USE_PRIVATE_LIBGCC
 ifeq ($(CONFIG_USE_PRIVATE_LIBGCC),y)
 PLATFORM_LIBGCC = arch/$(ARCH)/lib/lib.a
 else
-PLATFORM_LIBGCC = -L $(CONFIG_USE_PRIVATE_LIBGCC) -lgcc
-endif
-else
 PLATFORM_LIBGCC := -L $(shell dirname `$(CC) $(c_flags) -print-libgcc-file-name`) -lgcc
 endif
 PLATFORM_LIBS += $(PLATFORM_LIBGCC)