dt-bindings: clock: meson8b: drop the "ABP" clock definition

dt-bindings: clock: meson8b: drop the "ABP" clock definition

Commit 8e1dd17c8b0e3f ("dt-bindings: clock: meson8b: export the CPU post
dividers") added a new clock ID "CLKID_ABP" which contains a typo. This
was fixed by adding a new (typo-free) #define CLKID_APB in
commit 40d08f774c17ad ("dt-bindings: clock: meson8b: add APB clock
definition").
Now that the new #define is used by the driver we can remove the old
one (because the old one is not used anywhere).

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lkml.kernel.org/r/20190319214123.27219-2-martin.blumenstingl@googlemail.com