ARM: dts: stm32: Add GPIO LEDs for STM32MP1 DHCOM PDK2

Add bindings for the four GPIO LEDs on DH PDK2 board. Note that LED5
GPIO-E may conflict with touchscreen interrupt, hence LED5 must be
disabled when using the DH 560-200 display unit with touchscreen.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: Patrick Delaunay <patrick.delaunay@st.com>
Cc: linux-stm32@st-md-mailman.stormreply.com
To: linux-arm-kernel@lists.infradead.org
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>