Update Linux to v5.4.148

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz

Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/scripts/gdb/linux/rbtree.py b/scripts/gdb/linux/rbtree.py
index 39db889..c4b9916 100644
--- a/scripts/gdb/linux/rbtree.py
+++ b/scripts/gdb/linux/rbtree.py
@@ -12,7 +12,7 @@
 
 def rb_first(root):
     if root.type == rb_root_type.get_type():
-        node = node.address.cast(rb_root_type.get_type().pointer())
+        node = root.address.cast(rb_root_type.get_type().pointer())
     elif root.type != rb_root_type.get_type().pointer():
         raise gdb.GdbError("Must be struct rb_root not {}".format(root.type))
 
@@ -28,7 +28,7 @@
 
 def rb_last(root):
     if root.type == rb_root_type.get_type():
-        node = node.address.cast(rb_root_type.get_type().pointer())
+        node = root.address.cast(rb_root_type.get_type().pointer())
     elif root.type != rb_root_type.get_type().pointer():
         raise gdb.GdbError("Must be struct rb_root not {}".format(root.type))