Memory traits wrong for STM32F7 DTCM

[chris-durand]

The memory traits for the Cortex-M7 DTCM memory are hard-coded to 0x2013 for all devices in the linker script macros. Bit 3 "DMA-capable" is not set, which is not correct for STM32F7 devices.

Those permit DMA access to the DTCM through the AHBS slave interface:

I don't know if this bug has any practical consequences. I found it by accident while looking at an STM32F7 linker script.