MIPS: Fix off-by-one in pci_resource_to_user()

The MIPS implementation of pci_resource_to_user() introduced in v3.12 by
commit 4c2924b ("MIPS: PCI: Use pci_resource_to_user to map pci
memory space properly") incorrectly sets *end to the address of the
byte after the resource, rather than the last byte of the resource.

This results in userland seeing resources as a byte larger than they
actually are, for example a 32 byte BAR will be reported by a tool such
as lspci as being 33 bytes in size:

    Region 2: I/O ports at 1000 [disabled] [size=33]

Correct this by subtracting one from the calculated end address,
reporting the correct address to userland.

Signed-off-by: Paul Burton <[email protected]>
Reported-by: Rui Wang <[email protected]>
Fixes: 4c2924b ("MIPS: PCI: Use pci_resource_to_user to map pci memory space properly")
Cc: James Hogan <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Wolfgang Grandegger <[email protected]>
Cc: [email protected]
Cc: [email protected] # v3.12+
Patchwork: https://patchwork.linux-mips.org/patch/19829/

arch/mips/pci/pci.c

@@ -54,5 +54,5 @@ void pci_resource_to_user(const struct pci_dev *dev, int bar,
 	phys_addr_t size = resource_size(rsrc);
 
 	*start = fixup_bigphys_addr(rsrc->start, size);
-	*end = rsrc->start + size;
+	*end = rsrc->start + size - 1;
 }