Remove some quirks from the memory map

The correct amount of space is now reserved for Kbuffs, and there's no
need to have a 1MB gap where the old PhysicalAccess window was.

Tested on Raspberry Pi 4

hdr/KernelWS

@@ -295,9 +295,8 @@ IRQStackAddress     ASpace IRQStackSize, &100000
 SVCStackAddress     ASpace SVCStackSize, &100000
 ABTStackAddress     ASpace ABTStackSize, &100000
 UNDStackAddress     ASpace UNDStackSize, &100000
-                    ASpace &00100000, &100000 ; spare since PhysicalAddress moved
 DCacheCleanAddress  ASpace &00040000, &10000 ; eg. for StrongARM, 256k of space
-KbuffsBaseAddress   ASpace &000A8000 ; kernel buffers for long command lines, size KbuffsMaxSize
+KbuffsBaseAddress   ASpace KbuffsMaxSize ; kernel buffers for long command lines
 HALWorkspaceNCNB    ASpace &00008000 ; 32K of uncacheable HAL workspace (if requested)
 L2PT                ASpace &00400000, &400000
 L1PT                ASpace &00004000