binutils: fix static linking

pkg-autotools.mk already handles static/shared linking, so no need to
explictly force it. Worse even, the build fails with BR2_PREFER_STATIC_LINK
as we end up calling libtool with --static when it tries to link the .so,
breaking the build:

../ld: attempted static link of dynamic object
`../opcodes/.libs/libopcodes.so'
collect2: error: ld returned 1 exit status

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/binutils/binutils.mk

@@ -39,7 +39,6 @@ BINUTILS_LICENSE_FILES = COPYING3 COPYING.LIB
 BINUTILS_CONF_OPT = --disable-multilib --disable-werror \
 		--host=$(GNU_TARGET_NAME) \
 		--target=$(GNU_TARGET_NAME) \
-		--enable-shared \
 		$(BINUTILS_EXTRA_CONFIG_OPTIONS)
 
 # Install binutils after busybox to prefer full-blown utilities