valgrind: allow selection on aarch64

valgrind works fine on aarch64, so allow selecting it on that
architecture.

Signed-off-by: Anssi Hannula <anssi.hannula@bitwise.fi>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/valgrind/Config.in

@@ -1,5 +1,6 @@
 config BR2_PACKAGE_VALGRIND_ARCH_SUPPORTS
 	bool
+	default y if BR2_aarch64
 	default y if BR2_ARM_CPU_ARMV7A
 	default y if BR2_mips || BR2_mipsel || BR2_mips64 || BR2_mips64el
 	default y if BR2_i386 || BR2_x86_64