ARM: dts: sun7i: bananapi-m1-plus: Unify suffix for board specific labels

The dts file uses "bananapi" for some labels and "bananapim1plus" for
other. Use the shortened "bpi_m1p" suffix for all board specific labels.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>