Remove unused parameter from HASH1 dmas property on stm32mp157c SoC.

Fixes: 1e726a40 ("ARM: dts: stm32: Add HASH support on stm32mp157c")
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>
[Olof: Bug doesn't cause any harm, so shouldn't need stable backport]
Signed-off-by: Olof Johansson <olof@lixom.net>