dts: arm: stm32: add support for STM32F105xx parts

The STM32F105xx is effectively an STM32F107xx without Ethernet. As such,
it's possible to include the STM32F105's device tree from STM32F107, and
add in any additional nodes (currently just DMA2, though according to
the datasheet, this may be supported by the STM32F105xx and other parts
too).

Signed-off-by: Attie Grande <attie.grande@argentum-systems.co.uk>