Revert "px5g-standalone: provide px5g via PROVIDES"

Revert "px5g-standalone: provide px5g via PROVIDES"

This reverts commit cc66f819b4e778732a32f08f5dc39a2554682b73.

This commit causes opkg to install px5g-standalone instead of px5g when
installing luci-ssl. As luci-ssl depends on mbedtls, using
px5g-standalone makes no sense. Next to that, it creates deprecated SHA1
certificates. Revert the commit to avoid pxg5-standalone to be
installed by accident.

Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>
(cherry picked from commit ca8aee0c570561fc59fb0d0e6b5eac418054c372)