Fix ARM uclibc build with !BR2_UCLIBC_ARM_BX.

When BR2_UCLIBC_ARM_BX is not set, UCLIBC_OPT_UNSET gets called with an extra
argument.  Remove it.

Signed-off-by: Justin Maggard <jmaggard10@gmail.com>
Acked-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/uclibc/uclibc.mk

@@ -85,7 +85,7 @@ define UCLIBC_ARM_BX_CONFIG
 endef
 else
 define UCLIBC_ARM_BX_CONFIG
-	$(call UCLIBC_OPT_UNSET,USE_BX,y,$(@D))
+	$(call UCLIBC_OPT_UNSET,USE_BX,$(@D))
 endef
 endif