pbio/platform/ev3/platform.ld: reserve more for stack

The start.S script is already reserving 2.8M for the stack via:

        .set  UND_STACK_SIZE, 0x50000
        .set  ABT_STACK_SIZE, 0x50000
        .set  FIQ_STACK_SIZE, 0xF0000
        .set  IRQ_STACK_SIZE, 0xF0000
        .set  SVC_STACK_SIZE, 0x50000

And expects a bit more for the main stack. 64K was not nearly enough
to cover this. 4M should be more than enough.

Author: dlech

lib/pbio/platform/ev3/platform.ld

@@ -10,7 +10,7 @@ MEMORY
     DDR        (rwx) : ORIGIN = 0xC0008000, LENGTH = (64M - 0x8000)
 }
 
-_minimal_stack_size = 64K;
+_minimal_stack_size = 4M;
 pbdrv_stack_end = ORIGIN(DDR) + LENGTH(DDR) - 4;
 
 SECTIONS