ME: Let kernel code on the main CPU reach RAM and VRAM through kseg1

Yabause-PSP's me.prx ORs 0xA0000000 onto its own addresses to share a
buffer with the ME uncached, which is 0xA8xxxxxx for a module in kernel
RAM. The main CPU's space has no views there, so it crashed.

All of kernel segment 1 (0xA0000000-0xBFFFFFFF) now counts as MMIO, and a
device below the hardware registers maps RAM and VRAM onto their uncached
mirrors at 0x40000000. The main CPU's native kernel loads and stores send
the whole segment to that path; the ME keeps 0xBC000000 as the boundary,
since its space maps the rest.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Core/MemMap.h

@@ -409,9 +409,11 @@ inline bool IsDepthTexVRAMAddress(const u32 address) {
 	return ((address & 0xBFE00000) == 0x04200000) || ((address & 0xBFE00000) == 0x04600000);
 }
 
-// TODO: To re-evaluate.
+// Kernel segment 1 (0xA0000000-0xBFFFFFFF): the hardware registers from 0xBC000000, and below them
+// uncached RAM and VRAM, which only the Media Engine's space maps. Kernel code reaches the rest
+// through MMIO::Read/Write.
 inline bool IsMMIOAccess(const u32 address) {
-	return ((address & 0xFC000000) == 0xBC000000);
+	return (address & 0xE0000000) == 0xA0000000;
 }
 
 // 0x08000000 -> 0x08800000