package/volk: fix Config.in syntax error

Fixes:
package/volk/Config.in:4: syntax error
package/volk/Config.in:3: invalid option

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/volk/Config.in

@@ -1,6 +1,6 @@
 comment "volk needs a toolchain w/ C++, NPTL, wchar, dynamic library"
 	depends on BR2_USE_MMU
-	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_GCC_AT_LEAST_7 \
+	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_GCC_AT_LEAST_7 || \
 		!BR2_TOOLCHAIN_HAS_THREADS_NPTL || BR2_STATIC_LIBS
 
 config BR2_PACKAGE_VOLK