Fix a thermal zone name for consistency with the other SoCs:
MFG contains GPU, the latter is more specific and must be used here.
The naming must be fixed "atomically" so compilation does not break.
As a result, the change is made in the dt-bindings and in the LVTS
driver within a single commit, despite the checkpatch warning.
The definition can be modified safely here because it is used only
in the LVTS driver, which is modified accordingly.
Fixes: a2ca202350f9 ("dt-bindings: thermal: mediatek: Add LVTS thermal controller definition for MT8186")
Signed-off-by: Julien Panis <jpanis@xxxxxxxxxxxx>