package/libvirt: fix ssh2 option

Fix the following build failure raised since commit
fbf25acfbfd5a73b3560918bea081768abbe5723:

output/build/libvirt-7.7.0/meson.build:1:0: ERROR: Unknown options: "ssh2"

Fixes:
 - No autobuilder failures (yet)

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/libvirt/libvirt.mk

@@ -220,10 +220,10 @@ LIBVIRT_CONF_OPTS += -Dsasl=disabled
 endif
 
 ifeq ($(BR2_PACKAGE_LIBSSH2),y)
-LIBVIRT_CONF_OPTS += -Dssh2=enabled
+LIBVIRT_CONF_OPTS += -Dlibssh2=enabled
 LIBVIRT_DEPENDENCIES += libssh2
 else
-LIBVIRT_CONF_OPTS += -Dssh2=disabled
+LIBVIRT_CONF_OPTS += -Dlibssh2=disabled
 endif
 
 ifeq ($(BR2_PACKAGE_LIBVIRT_LXC),y)