logger CHANGE rename ly_verb() to ly_log_level()

Align the setter function with the LY_LOG_LEVEL enums to simplify their
association.
diff --git a/src/xpath.c b/src/xpath.c
index ba16ede..19ec938 100644
--- a/src/xpath.c
+++ b/src/xpath.c
@@ -134,7 +134,7 @@
     uint16_t i, j;
     char tmp[128];
 
-    if (!exp || (ly_log_level < LY_LLDBG)) {
+    if (!exp || (ly_ll < LY_LLDBG)) {
         return;
     }
 
@@ -168,7 +168,7 @@
     struct lyxp_set_node *item;
     struct lyxp_set_scnode *sitem;
 
-    if (ly_log_level < LY_LLDBG) {
+    if (ly_ll < LY_LLDBG) {
         return;
     }