MT#55033 Restore provisioning.bootstrap_method 'none' value

The method 'none' was added is commit 63815c948 as dedicated
request from a customer to support provisioning of phones
without ZRP.

During future changes to the supported values, in the commit
34273a837 the 'none' value got lost by mistake.

This commit will re-add support for the 'none' value.

Change-Id: Ia1b0367923b15e55c1dcfb69655bd23954033c77

db_scripts/diff/15786.down

@@ -0,0 +1,6 @@
+USE provisioning;
+SET autocommit=0;
+
+ALTER TABLE autoprov_devices CHANGE COLUMN bootstrap_method bootstrap_method ENUM('http','redirect_panasonic','redirect_yealink','redirect_polycom','redirect_snom','redirect_grandstream','redirect_ale') NULL DEFAULT 'http' ;
+
+COMMIT;

db_scripts/diff/15786.up

@@ -0,0 +1,6 @@
+USE provisioning;
+SET autocommit=0;
+
+ALTER TABLE autoprov_devices CHANGE COLUMN bootstrap_method bootstrap_method ENUM('http','redirect_panasonic','redirect_yealink','redirect_polycom','redirect_snom','redirect_grandstream','redirect_ale','none') NULL DEFAULT 'http' ;
+
+COMMIT;