[FREELDR] Fix UEFI IA-32 boot (#8886)

The PAE flag might be enabled on some x86-32 UEFI platforms, causing a crash in the kernel.
```
Assertion C:\reactos-master\reactos\ntoskrnl\mm\ARM3\miarm.h(971): PointerPte->u.Hard.Valid == 0
nt!MI_WRITE_VALID_PTE+0x28:
822d1d08 cd2c            int     2Ch
```

Tested using qemu with `OVMF32_CODE_4M.fd` firmware, and with 32bit UEFI in VMware.

boot/freeldr/freeldr/ntldr/arch/i386/winldr.c

@@ -455,6 +455,12 @@ WinLdrSetProcessorContext(
     /* Re-initialize EFLAGS */
     __writeeflags(0);
 
+    /* Disable paging first before disabling PAE to avoid crash
+     * because UEFI might have enabled paged mode with PAE.
+     * Our kernel doesn't support PAE, so disable it. */
+    __writecr0(__readcr0() & ~CR0_PG);
+    __writecr4(__readcr4() & ~CR4_PAE);
+
     /* Set the PDBR */
     __writecr3((ULONG_PTR)PDE);