Fix compressed ROM support

When PhysRamTable was updated to store addresses in page units instead
of byte units (commit df4efb68), the code which allocates the ROM
decompression workspace didn't get updated, causing it to break. Add a
few extra shifts to the code in order to account for the changes.

Fixes issue reported on forums with (compressed) OMAP3 ROM failing to
boot: https://www.riscosopen.org/forum/forums/5/topics/16446

s/HAL

@@ -1392,22 +1392,22 @@ ROMDecompAlign_$pt * 20
         STR     v7, [sp, #8] ; Overwrite stacked WS size
         MOV     v6, #ROMDecompWSAddr_$pt ; Current log addr
 26
-        ADD     v2, v2, v5
-        BIC     v2, v2, v5 ; MB-aligned physram
+        ADD     v2, v2, v5, LSR #12
+        BIC     v2, v2, v5, LSR #12 ; MB-aligned physram
         LDMIA   v1, {a2, a3}
-        SUB     a2, v2, a2 ; Amount of bank used
-        SUB     a2, a3, a2 ; Amount of bank remaining
-        MOVS    a2, a2, ASR #ROMDecompAlign_$pt ; Round down to nearest MB
+        SUB     a2, v2, a2 ; Amount of bank used (page units)
+        RSB     a2, a2, a3, LSR #12 ; Amount of bank remaining (page units)
+        MOVS    a2, a2, ASR #ROMDecompAlign_$pt-12 ; Round down to nearest MB
         LDRLE   v2, [v1, #8]! ; Move to next bank if 0MB left
         BLE     %BT26
         CMP     a2, v7, LSR #ROMDecompAlign_$pt
         MOVHS   a4, v7
         MOVLO   a4, a2, LSL #ROMDecompAlign_$pt ; a4 = amount to take
-        MOV     a1, v2 ; set up parameters for MapIn call
+        MOV     a1, v2, LSL #12 ; set up parameters for MapIn call
         MOV     a2, v6
         MOV     a3, #OSAP_None
         SUB     v7, v7, a4 ; Decrease amount to allocate
-        ADD     v2, v2, a4 ; Increase physram ptr
+        ADD     v2, v2, a4, LSR #12 ; Increase physram ptr
         ADD     v6, v6, a4 ; Increase logram ptr
         BL      Init_MapIn_$pt
         CMP     v7, #0