dev: IDE Disk: Handle bad IDE image size

Handle bad IDE disk image size 0. When image size is 0, gem5 will cause an
exception with log "Floating point exception (core dumped)".

Committed by: Nilay Vaish <nilay@cs.wisc.edu>

src/dev/ide_disk.cc

@@ -90,6 +90,8 @@ IdeDisk::IdeDisk(const Params *p)
     } else {
         if (lba_size >= 63)
             sectors = 63;
+        else if (lba_size == 0)
+            panic("Bad IDE image size: 0\n");
         else
             sectors = lba_size;