fix: update linked Customer on Patient update only if Link Customer to Patient is enabled (#25926)

diff --git a/erpnext/healthcare/doctype/patient/patient.py b/erpnext/healthcare/doctype/patient/patient.py
index 789d452..cebcb20 100644
--- a/erpnext/healthcare/doctype/patient/patient.py
+++ b/erpnext/healthcare/doctype/patient/patient.py
@@ -33,21 +33,21 @@
 		self.reload() # self.notify_update()
 
 	def on_update(self):
-		if self.customer:
-			customer = frappe.get_doc('Customer', self.customer)
-			if self.customer_group:
-				customer.customer_group = self.customer_group
-			if self.territory:
-				customer.territory = self.territory
+		if frappe.db.get_single_value('Healthcare Settings', 'link_customer_to_patient'):
+			if self.customer:
+				customer = frappe.get_doc('Customer', self.customer)
+				if self.customer_group:
+					customer.customer_group = self.customer_group
+				if self.territory:
+					customer.territory = self.territory
 
-			customer.customer_name = self.patient_name
-			customer.default_price_list = self.default_price_list
-			customer.default_currency = self.default_currency
-			customer.language = self.language
-			customer.ignore_mandatory = True
-			customer.save(ignore_permissions=True)
-		else:
-			if frappe.db.get_single_value('Healthcare Settings', 'link_customer_to_patient'):
+				customer.customer_name = self.patient_name
+				customer.default_price_list = self.default_price_list
+				customer.default_currency = self.default_currency
+				customer.language = self.language
+				customer.ignore_mandatory = True
+				customer.save(ignore_permissions=True)
+			else:
 				create_customer(self)
 
 	def set_full_name(self):