stdlib, python: Add warning message and clarify binary vs metric units (#1479)

This PR changes memory and cache sizes in various parts of the gem5
codebase to use binary units (e.g. KiB) instead of metric units (e.g.
kB). This makes the codebase more consistent, as gem5 automatically
converts memory and cache sizes that are in metric units to binary
units.

This PR also adds a warning message to let users know when an
auto-conversion from base 10 to base 2 units occurs.

There were a few places in configs and in the comments of various files
where I didn't change the metric units, as I couldn't figure out where
the parameters with those units were being used.

src/dev/arm/RealView.py

@@ -1189,8 +1189,8 @@ class VExpress_GEM5_Base(RealView):
     Memory map:
        0x00000000-0x03ffffff: Boot memory (CS0)
        0x04000000-0x07ffffff: Trusted Memory/Reserved
-            0x04000000-0x0403FFFF: 256kB Trusted SRAM
-            0x06000000-0x07ffffff: 32MB Trusted DRAM
+            0x04000000-0x0403FFFF: 256KiB Trusted SRAM
+            0x06000000-0x07ffffff: 32MiB Trusted DRAM
        0x08000000-0x0bffffff: NOR FLASH0 (CS0 alias)
        0x0c000000-0x0fffffff: NOR FLASH1 (Off-chip, CS4)
        0x10000000-0x13ffffff: gem5-specific peripherals (Off-chip, CS5)
@@ -1316,7 +1316,7 @@ class VExpress_GEM5_Base(RealView):
     # Trusted DRAM
     # TODO: preventing access from unsecure world to the trusted RAM
     trusted_dram = SimpleMemory(
-        range=AddrRange(0x06000000, size="32MB"), conf_table_reported=False
+        range=AddrRange(0x06000000, size="32MiB"), conf_table_reported=False
     )
     # Non-Trusted SRAM
     non_trusted_sram = MmioSRAM(
@@ -1454,7 +1454,7 @@ class VExpress_GEM5_Base(RealView):
 
     # VRAM
     vram = SimpleMemory(
-        range=AddrRange(0x18000000, size="32MB"), conf_table_reported=False
+        range=AddrRange(0x18000000, size="32MiB"), conf_table_reported=False
     )
 
     def _off_chip_devices(self):

src/dev/riscv/HiFive.py

@@ -183,7 +183,7 @@ class HiFive(HiFiveBase):
     # PCI
     pci_host = GenericRiscvPciHost(
         conf_base=0x30000000,
-        conf_size="256MB",
+        conf_size="256MiB",
         conf_device_bits=12,
         pci_pio_base=0x2F000000,
         pci_mem_base=0x40000000,