HAL_ChibiOS: use SRAM1 as first ram segment on H7

this is needed to give the linker more than 128k for static variables
with double precision maths.

libraries/AP_HAL_ChibiOS/hwdef/scripts/STM32H743xx.py

@@ -26,8 +26,8 @@ mcu = {
     # flags of 2 means faster memory for CPU intensive work
     # flags of 4 means memory can be used for SDMMC DMA
     'RAM_MAP' : [
-        (0x20000000, 128, 2), # DTCM, tightly coupled, no DMA, fast
         (0x30000000, 256, 0), # SRAM1, SRAM2
+        (0x20000000, 128, 2), # DTCM, tightly coupled, no DMA, fast
         (0x24000000, 512, 4), # AXI SRAM. Use this for SDMMC IDMA ops
         (0x00000400,  63, 2), # ITCM (first 1k removed, to keep address 0 unused)
         (0x30040000,  32, 0), # SRAM3.