scripts: kconfigfunctions: Redefine dt_nodelabel_has_compat()

The function in its current form is confusing because unlike other
similarly named functions (dt_nodelabel_has_prop(), dt_node_has_prop())
or devicetree macros (DT_NODE_HAS_COMPAT(), DT_NODE_HAS_PROP()), this
function takes into account the status of the checked node and returns
"y" only when the node is enabled.
This commit redefines dt_nodelabel_has_compat() so that it no longer
checks the node status, and for cases where the previous functionality
is needed, a new function named dt_nodelabel_enabled_with_compat()
is introduced as a replacement.

Signed-off-by: Andrzej Głąbek <andrzej.glabek@nordicsemi.no>