firewire: core: fix upper bound of possible CSR allocations

region->end is defined as an upper bound of the requested address range,
exclusive --- i.e. as an address outside of the range in which the
requested CSR is to be placed.

Hence 0x0001,0000,0000,0000 is the biggest valid region->end, not
0x0000,ffff,ffff,fffc like the current check asserted.

For simplicity, the fix drops the region->end & 3 test because there is
no actual problem with these bits set in region->end.  The allocated
address range will be quadlet aligned and of a size of multiple quadlets
due to the checks for region->start & 3 and handler->length & 3 alone.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/firewire/core-transaction.c

@@ -543,8 +543,8 @@ int fw_core_add_address_handler(struct fw_address_handler *handler,
 	int ret = -EBUSY;
 
 	if (region->start & 0xffff000000000003ULL ||
-	    region->end   & 0xffff000000000003ULL ||
 	    region->start >= region->end ||
+	    region->end   > 0x0001000000000000ULL ||
 	    handler->length & 3 ||
 	    handler->length == 0)
 		return -EINVAL;