package/qemu: remove comment about sh64

sh64 has been removed since commit [1]:

[1] 4338a319b72570e433fd7484f8a95e1e0e978941

Signed-off-by: Jugurtha BELKALEM <jugurtha.belkalem@smile.fr>
Reviewed-by: Thomas Huth <huth@tuxfamily.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/qemu/qemu.mk

@@ -186,7 +186,6 @@ HOST_QEMU_DEPENDENCIES = host-pkgconf host-zlib host-libglib2 host-pixman
 #       sh4eb           sh4eb
 #       sh4a            sh4
 #       sh4aeb          sh4eb
-#       sh64            not supported
 #       sparc           sparc
 #       sparc64         sparc64