bootloader: ARM: Fix mmu_free()

Allocation size was mixed up with page counts...
Allow freeing up to sNextVirtualAddress.

src/system/boot/arch/arm/arch_mmu.cpp

@@ -513,18 +513,18 @@ mmu_free(void *virtualAddress, size_t size)
 	TRACE(("mmu_free(virtualAddress = %p, size: %ld)\n", virtualAddress, size));
 
 	addr_t address = (addr_t)virtualAddress;
-	size = (size + B_PAGE_SIZE - 1) / B_PAGE_SIZE;
-		// get number of pages to map
+	addr_t pageOffset = address % B_PAGE_SIZE;
+	address -= pageOffset;
+	size = (size + pageOffset + B_PAGE_SIZE - 1) / B_PAGE_SIZE * B_PAGE_SIZE;
 
 	// is the address within the valid range?
-	if (address < KERNEL_BASE
-		|| address + size >= KERNEL_BASE + kMaxKernelSize) {
+	if (address < KERNEL_LOAD_BASE || address + size > sNextVirtualAddress) {
 		panic("mmu_free: asked to unmap out of range region (%p, size %lx)\n",
 			(void *)address, size);
 	}
 
 	// unmap all pages within the range
-	for (uint32 i = 0; i < size; i++) {
+	for (size_t i = 0; i < size; i += B_PAGE_SIZE) {
 		unmap_page(address);
 		address += B_PAGE_SIZE;
 	}